2 * drm_irq.c IRQ and vblank support
4 * \author Rickard E. (Rik) Faith <faith@valinux.com>
5 * \author Gareth Hughes <gareth@valinux.com>
9 * Created: Fri Mar 19 14:30:16 1999 by faith@valinux.com
11 * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
12 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
13 * All Rights Reserved.
15 * Permission is hereby granted, free of charge, to any person obtaining a
16 * copy of this software and associated documentation files (the "Software"),
17 * to deal in the Software without restriction, including without limitation
18 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
19 * and/or sell copies of the Software, and to permit persons to whom the
20 * Software is furnished to do so, subject to the following conditions:
22 * The above copyright notice and this permission notice (including the next
23 * paragraph) shall be included in all copies or substantial portions of the
26 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
27 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
28 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
29 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
30 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
31 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
32 * OTHER DEALINGS IN THE SOFTWARE.
36 #include "drm_trace.h"
38 #include <linux/interrupt.h> /* For task queue support */
39 #include <linux/slab.h>
41 #include <linux/vgaarb.h>
42 #include <linux/export.h>
44 /* Access macro for slots in vblank timestamp ringbuffer. */
45 #define vblanktimestamp(dev, crtc, count) \
46 ((dev)->vblank[crtc].time[(count) % DRM_VBLANKTIME_RBSIZE])
48 /* Retry timestamp calculation up to 3 times to satisfy
49 * drm_timestamp_precision before giving up.
51 #define DRM_TIMESTAMP_MAXRETRIES 3
53 /* Threshold in nanoseconds for detection of redundant
54 * vblank irq in drm_handle_vblank(). 1 msec should be ok.
56 #define DRM_REDUNDANT_VBLIRQ_THRESH_NS 1000000
59 * Clear vblank timestamp buffer for a crtc.
61 static void clear_vblank_timestamps(struct drm_device
*dev
, int crtc
)
63 memset(dev
->vblank
[crtc
].time
, 0, sizeof(dev
->vblank
[crtc
].time
));
67 * Disable vblank irq's on crtc, make sure that last vblank count
68 * of hardware and corresponding consistent software vblank counter
69 * are preserved, even if there are any spurious vblank irq's after
72 static void vblank_disable_and_save(struct drm_device
*dev
, int crtc
)
74 unsigned long irqflags
;
78 struct timeval tvblank
;
79 int count
= DRM_TIMESTAMP_MAXRETRIES
;
81 /* Prevent vblank irq processing while disabling vblank irqs,
82 * so no updates of timestamps or count can happen after we've
83 * disabled. Needed to prevent races in case of delayed irq's.
85 spin_lock_irqsave(&dev
->vblank_time_lock
, irqflags
);
87 dev
->driver
->disable_vblank(dev
, crtc
);
88 dev
->vblank
[crtc
].enabled
= false;
90 /* No further vblank irq's will be processed after
91 * this point. Get current hardware vblank count and
92 * vblank timestamp, repeat until they are consistent.
94 * FIXME: There is still a race condition here and in
95 * drm_update_vblank_count() which can cause off-by-one
96 * reinitialization of software vblank counter. If gpu
97 * vblank counter doesn't increment exactly at the leading
98 * edge of a vblank interval, then we can lose 1 count if
99 * we happen to execute between start of vblank and the
100 * delayed gpu counter increment.
103 dev
->vblank
[crtc
].last
= dev
->driver
->get_vblank_counter(dev
, crtc
);
104 vblrc
= drm_get_last_vbltimestamp(dev
, crtc
, &tvblank
, 0);
105 } while (dev
->vblank
[crtc
].last
!= dev
->driver
->get_vblank_counter(dev
, crtc
) && (--count
) && vblrc
);
110 /* Compute time difference to stored timestamp of last vblank
111 * as updated by last invocation of drm_handle_vblank() in vblank irq.
113 vblcount
= atomic_read(&dev
->vblank
[crtc
].count
);
114 diff_ns
= timeval_to_ns(&tvblank
) -
115 timeval_to_ns(&vblanktimestamp(dev
, crtc
, vblcount
));
117 /* If there is at least 1 msec difference between the last stored
118 * timestamp and tvblank, then we are currently executing our
119 * disable inside a new vblank interval, the tvblank timestamp
120 * corresponds to this new vblank interval and the irq handler
121 * for this vblank didn't run yet and won't run due to our disable.
122 * Therefore we need to do the job of drm_handle_vblank() and
123 * increment the vblank counter by one to account for this vblank.
125 * Skip this step if there isn't any high precision timestamp
126 * available. In that case we can't account for this and just
129 if ((vblrc
> 0) && (abs64(diff_ns
) > 1000000)) {
130 atomic_inc(&dev
->vblank
[crtc
].count
);
131 smp_mb__after_atomic();
134 /* Invalidate all timestamps while vblank irq's are off. */
135 clear_vblank_timestamps(dev
, crtc
);
137 spin_unlock_irqrestore(&dev
->vblank_time_lock
, irqflags
);
140 static void vblank_disable_fn(unsigned long arg
)
142 struct drm_vblank_crtc
*vblank
= (void *)arg
;
143 struct drm_device
*dev
= vblank
->dev
;
144 unsigned long irqflags
;
145 int crtc
= vblank
->crtc
;
147 if (!dev
->vblank_disable_allowed
)
150 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
151 if (atomic_read(&vblank
->refcount
) == 0 && vblank
->enabled
) {
152 DRM_DEBUG("disabling vblank on crtc %d\n", crtc
);
153 vblank_disable_and_save(dev
, crtc
);
155 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
159 * drm_vblank_cleanup - cleanup vblank support
162 * This function cleans up any resources allocated in drm_vblank_init.
164 void drm_vblank_cleanup(struct drm_device
*dev
)
168 /* Bail if the driver didn't call drm_vblank_init() */
169 if (dev
->num_crtcs
== 0)
172 for (crtc
= 0; crtc
< dev
->num_crtcs
; crtc
++) {
173 del_timer_sync(&dev
->vblank
[crtc
].disable_timer
);
174 vblank_disable_fn((unsigned long)&dev
->vblank
[crtc
]);
181 EXPORT_SYMBOL(drm_vblank_cleanup
);
184 * drm_vblank_init - initialize vblank support
186 * @num_crtcs: number of crtcs supported by @dev
188 * This function initializes vblank support for @num_crtcs display pipelines.
191 * Zero on success or a negative error code on failure.
193 int drm_vblank_init(struct drm_device
*dev
, int num_crtcs
)
195 int i
, ret
= -ENOMEM
;
197 spin_lock_init(&dev
->vbl_lock
);
198 spin_lock_init(&dev
->vblank_time_lock
);
200 dev
->num_crtcs
= num_crtcs
;
202 dev
->vblank
= kcalloc(num_crtcs
, sizeof(*dev
->vblank
), GFP_KERNEL
);
206 for (i
= 0; i
< num_crtcs
; i
++) {
207 dev
->vblank
[i
].dev
= dev
;
208 dev
->vblank
[i
].crtc
= i
;
209 init_waitqueue_head(&dev
->vblank
[i
].queue
);
210 setup_timer(&dev
->vblank
[i
].disable_timer
, vblank_disable_fn
,
211 (unsigned long)&dev
->vblank
[i
]);
214 DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
216 /* Driver specific high-precision vblank timestamping supported? */
217 if (dev
->driver
->get_vblank_timestamp
)
218 DRM_INFO("Driver supports precise vblank timestamp query.\n");
220 DRM_INFO("No driver support for vblank timestamp query.\n");
222 dev
->vblank_disable_allowed
= false;
227 drm_vblank_cleanup(dev
);
230 EXPORT_SYMBOL(drm_vblank_init
);
232 static void drm_irq_vgaarb_nokms(void *cookie
, bool state
)
234 struct drm_device
*dev
= cookie
;
236 if (dev
->driver
->vgaarb_irq
) {
237 dev
->driver
->vgaarb_irq(dev
, state
);
241 if (!dev
->irq_enabled
)
245 if (dev
->driver
->irq_uninstall
)
246 dev
->driver
->irq_uninstall(dev
);
248 if (dev
->driver
->irq_preinstall
)
249 dev
->driver
->irq_preinstall(dev
);
250 if (dev
->driver
->irq_postinstall
)
251 dev
->driver
->irq_postinstall(dev
);
256 * drm_irq_install - install IRQ handler
258 * @irq: IRQ number to install the handler for
260 * Initializes the IRQ related data. Installs the handler, calling the driver
261 * irq_preinstall() and irq_postinstall() functions before and after the
264 * This is the simplified helper interface provided for drivers with no special
265 * needs. Drivers which need to install interrupt handlers for multiple
266 * interrupts must instead set drm_device->irq_enabled to signal the DRM core
267 * that vblank interrupts are available.
270 * Zero on success or a negative error code on failure.
272 int drm_irq_install(struct drm_device
*dev
, int irq
)
275 unsigned long sh_flags
= 0;
277 if (!drm_core_check_feature(dev
, DRIVER_HAVE_IRQ
))
283 /* Driver must have been initialized */
284 if (!dev
->dev_private
)
287 if (dev
->irq_enabled
)
289 dev
->irq_enabled
= true;
291 DRM_DEBUG("irq=%d\n", irq
);
293 /* Before installing handler */
294 if (dev
->driver
->irq_preinstall
)
295 dev
->driver
->irq_preinstall(dev
);
297 /* Install handler */
298 if (drm_core_check_feature(dev
, DRIVER_IRQ_SHARED
))
299 sh_flags
= IRQF_SHARED
;
301 ret
= request_irq(irq
, dev
->driver
->irq_handler
,
302 sh_flags
, dev
->driver
->name
, dev
);
305 dev
->irq_enabled
= false;
309 if (!drm_core_check_feature(dev
, DRIVER_MODESET
))
310 vga_client_register(dev
->pdev
, (void *)dev
, drm_irq_vgaarb_nokms
, NULL
);
312 /* After installing handler */
313 if (dev
->driver
->irq_postinstall
)
314 ret
= dev
->driver
->irq_postinstall(dev
);
317 dev
->irq_enabled
= false;
318 if (!drm_core_check_feature(dev
, DRIVER_MODESET
))
319 vga_client_register(dev
->pdev
, NULL
, NULL
, NULL
);
327 EXPORT_SYMBOL(drm_irq_install
);
330 * drm_irq_uninstall - uninstall the IRQ handler
333 * Calls the driver's irq_uninstall() function and unregisters the IRQ handler.
334 * This should only be called by drivers which used drm_irq_install() to set up
335 * their interrupt handler. Other drivers must only reset
336 * drm_device->irq_enabled to false.
338 * Note that for kernel modesetting drivers it is a bug if this function fails.
339 * The sanity checks are only to catch buggy user modesetting drivers which call
340 * the same function through an ioctl.
343 * Zero on success or a negative error code on failure.
345 int drm_irq_uninstall(struct drm_device
*dev
)
347 unsigned long irqflags
;
351 if (!drm_core_check_feature(dev
, DRIVER_HAVE_IRQ
))
354 irq_enabled
= dev
->irq_enabled
;
355 dev
->irq_enabled
= false;
358 * Wake up any waiters so they don't hang.
360 if (dev
->num_crtcs
) {
361 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
362 for (i
= 0; i
< dev
->num_crtcs
; i
++) {
363 wake_up(&dev
->vblank
[i
].queue
);
364 dev
->vblank
[i
].enabled
= false;
365 dev
->vblank
[i
].last
=
366 dev
->driver
->get_vblank_counter(dev
, i
);
368 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
374 DRM_DEBUG("irq=%d\n", dev
->irq
);
376 if (!drm_core_check_feature(dev
, DRIVER_MODESET
))
377 vga_client_register(dev
->pdev
, NULL
, NULL
, NULL
);
379 if (dev
->driver
->irq_uninstall
)
380 dev
->driver
->irq_uninstall(dev
);
382 free_irq(dev
->irq
, dev
);
386 EXPORT_SYMBOL(drm_irq_uninstall
);
391 * \param inode device inode.
392 * \param file_priv DRM file private.
393 * \param cmd command.
394 * \param arg user argument, pointing to a drm_control structure.
395 * \return zero on success or a negative number on failure.
397 * Calls irq_install() or irq_uninstall() according to \p arg.
399 int drm_control(struct drm_device
*dev
, void *data
,
400 struct drm_file
*file_priv
)
402 struct drm_control
*ctl
= data
;
405 /* if we haven't irq we fallback for compatibility reasons -
406 * this used to be a separate function in drm_dma.h
409 if (!drm_core_check_feature(dev
, DRIVER_HAVE_IRQ
))
411 if (drm_core_check_feature(dev
, DRIVER_MODESET
))
413 /* UMS was only ever support on pci devices. */
414 if (WARN_ON(!dev
->pdev
))
418 case DRM_INST_HANDLER
:
419 irq
= dev
->pdev
->irq
;
421 if (dev
->if_version
< DRM_IF_VERSION(1, 2) &&
424 mutex_lock(&dev
->struct_mutex
);
425 ret
= drm_irq_install(dev
, irq
);
426 mutex_unlock(&dev
->struct_mutex
);
429 case DRM_UNINST_HANDLER
:
430 mutex_lock(&dev
->struct_mutex
);
431 ret
= drm_irq_uninstall(dev
);
432 mutex_unlock(&dev
->struct_mutex
);
441 * drm_calc_timestamping_constants - calculate vblank timestamp constants
442 * @crtc: drm_crtc whose timestamp constants should be updated.
443 * @mode: display mode containing the scanout timings
445 * Calculate and store various constants which are later
446 * needed by vblank and swap-completion timestamping, e.g,
447 * by drm_calc_vbltimestamp_from_scanoutpos(). They are
448 * derived from CRTC's true scanout timing, so they take
449 * things like panel scaling or other adjustments into account.
451 void drm_calc_timestamping_constants(struct drm_crtc
*crtc
,
452 const struct drm_display_mode
*mode
)
454 int linedur_ns
= 0, pixeldur_ns
= 0, framedur_ns
= 0;
455 int dotclock
= mode
->crtc_clock
;
457 /* Valid dotclock? */
459 int frame_size
= mode
->crtc_htotal
* mode
->crtc_vtotal
;
462 * Convert scanline length in pixels and video
463 * dot clock to line duration, frame duration
464 * and pixel duration in nanoseconds:
466 pixeldur_ns
= 1000000 / dotclock
;
467 linedur_ns
= div_u64((u64
) mode
->crtc_htotal
* 1000000, dotclock
);
468 framedur_ns
= div_u64((u64
) frame_size
* 1000000, dotclock
);
471 * Fields of interlaced scanout modes are only half a frame duration.
473 if (mode
->flags
& DRM_MODE_FLAG_INTERLACE
)
476 DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",
479 crtc
->pixeldur_ns
= pixeldur_ns
;
480 crtc
->linedur_ns
= linedur_ns
;
481 crtc
->framedur_ns
= framedur_ns
;
483 DRM_DEBUG("crtc %d: hwmode: htotal %d, vtotal %d, vdisplay %d\n",
484 crtc
->base
.id
, mode
->crtc_htotal
,
485 mode
->crtc_vtotal
, mode
->crtc_vdisplay
);
486 DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",
487 crtc
->base
.id
, dotclock
, framedur_ns
,
488 linedur_ns
, pixeldur_ns
);
490 EXPORT_SYMBOL(drm_calc_timestamping_constants
);
493 * drm_calc_vbltimestamp_from_scanoutpos - precise vblank timestamp helper
495 * @crtc: Which CRTC's vblank timestamp to retrieve
496 * @max_error: Desired maximum allowable error in timestamps (nanosecs)
497 * On return contains true maximum error of timestamp
498 * @vblank_time: Pointer to struct timeval which should receive the timestamp
499 * @flags: Flags to pass to driver:
501 * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler
502 * @refcrtc: CRTC which defines scanout timing
503 * @mode: mode which defines the scanout timings
505 * Implements calculation of exact vblank timestamps from given drm_display_mode
506 * timings and current video scanout position of a CRTC. This can be called from
507 * within get_vblank_timestamp() implementation of a kms driver to implement the
508 * actual timestamping.
510 * Should return timestamps conforming to the OML_sync_control OpenML
511 * extension specification. The timestamp corresponds to the end of
512 * the vblank interval, aka start of scanout of topmost-leftmost display
513 * pixel in the following video frame.
515 * Requires support for optional dev->driver->get_scanout_position()
516 * in kms driver, plus a bit of setup code to provide a drm_display_mode
517 * that corresponds to the true scanout timing.
519 * The current implementation only handles standard video modes. It
520 * returns as no operation if a doublescan or interlaced video mode is
521 * active. Higher level code is expected to handle this.
524 * Negative value on error, failure or if not supported in current
527 * -EINVAL - Invalid CRTC.
528 * -EAGAIN - Temporary unavailable, e.g., called before initial modeset.
529 * -ENOTSUPP - Function not supported in current display mode.
530 * -EIO - Failed, e.g., due to failed scanout position query.
532 * Returns or'ed positive status flags on success:
534 * DRM_VBLANKTIME_SCANOUTPOS_METHOD - Signal this method used for timestamping.
535 * DRM_VBLANKTIME_INVBL - Timestamp taken while scanout was in vblank interval.
538 int drm_calc_vbltimestamp_from_scanoutpos(struct drm_device
*dev
, int crtc
,
540 struct timeval
*vblank_time
,
542 const struct drm_crtc
*refcrtc
,
543 const struct drm_display_mode
*mode
)
545 struct timeval tv_etime
;
546 ktime_t stime
, etime
;
549 int framedur_ns
, linedur_ns
, pixeldur_ns
, delta_ns
, duration_ns
;
552 if (crtc
< 0 || crtc
>= dev
->num_crtcs
) {
553 DRM_ERROR("Invalid crtc %d\n", crtc
);
557 /* Scanout position query not supported? Should not happen. */
558 if (!dev
->driver
->get_scanout_position
) {
559 DRM_ERROR("Called from driver w/o get_scanout_position()!?\n");
563 /* Durations of frames, lines, pixels in nanoseconds. */
564 framedur_ns
= refcrtc
->framedur_ns
;
565 linedur_ns
= refcrtc
->linedur_ns
;
566 pixeldur_ns
= refcrtc
->pixeldur_ns
;
568 /* If mode timing undefined, just return as no-op:
569 * Happens during initial modesetting of a crtc.
571 if (framedur_ns
== 0) {
572 DRM_DEBUG("crtc %d: Noop due to uninitialized mode.\n", crtc
);
576 /* Get current scanout position with system timestamp.
577 * Repeat query up to DRM_TIMESTAMP_MAXRETRIES times
578 * if single query takes longer than max_error nanoseconds.
580 * This guarantees a tight bound on maximum error if
581 * code gets preempted or delayed for some reason.
583 for (i
= 0; i
< DRM_TIMESTAMP_MAXRETRIES
; i
++) {
585 * Get vertical and horizontal scanout position vpos, hpos,
586 * and bounding timestamps stime, etime, pre/post query.
588 vbl_status
= dev
->driver
->get_scanout_position(dev
, crtc
, flags
, &vpos
,
589 &hpos
, &stime
, &etime
);
591 /* Return as no-op if scanout query unsupported or failed. */
592 if (!(vbl_status
& DRM_SCANOUTPOS_VALID
)) {
593 DRM_DEBUG("crtc %d : scanoutpos query failed [%d].\n",
598 /* Compute uncertainty in timestamp of scanout position query. */
599 duration_ns
= ktime_to_ns(etime
) - ktime_to_ns(stime
);
601 /* Accept result with < max_error nsecs timing uncertainty. */
602 if (duration_ns
<= *max_error
)
606 /* Noisy system timing? */
607 if (i
== DRM_TIMESTAMP_MAXRETRIES
) {
608 DRM_DEBUG("crtc %d: Noisy timestamp %d us > %d us [%d reps].\n",
609 crtc
, duration_ns
/1000, *max_error
/1000, i
);
612 /* Return upper bound of timestamp precision error. */
613 *max_error
= duration_ns
;
615 /* Check if in vblank area:
616 * vpos is >=0 in video scanout area, but negative
617 * within vblank area, counting down the number of lines until
620 invbl
= vbl_status
& DRM_SCANOUTPOS_INVBL
;
622 /* Convert scanout position into elapsed time at raw_time query
623 * since start of scanout at first display scanline. delta_ns
624 * can be negative if start of scanout hasn't happened yet.
626 delta_ns
= vpos
* linedur_ns
+ hpos
* pixeldur_ns
;
628 if (!drm_timestamp_monotonic
)
629 etime
= ktime_mono_to_real(etime
);
631 /* save this only for debugging purposes */
632 tv_etime
= ktime_to_timeval(etime
);
633 /* Subtract time delta from raw timestamp to get final
634 * vblank_time timestamp for end of vblank.
637 etime
= ktime_add_ns(etime
, -delta_ns
);
639 etime
= ktime_sub_ns(etime
, delta_ns
);
640 *vblank_time
= ktime_to_timeval(etime
);
642 DRM_DEBUG("crtc %d : v %d p(%d,%d)@ %ld.%ld -> %ld.%ld [e %d us, %d rep]\n",
643 crtc
, (int)vbl_status
, hpos
, vpos
,
644 (long)tv_etime
.tv_sec
, (long)tv_etime
.tv_usec
,
645 (long)vblank_time
->tv_sec
, (long)vblank_time
->tv_usec
,
646 duration_ns
/1000, i
);
648 vbl_status
= DRM_VBLANKTIME_SCANOUTPOS_METHOD
;
650 vbl_status
|= DRM_VBLANKTIME_INVBL
;
654 EXPORT_SYMBOL(drm_calc_vbltimestamp_from_scanoutpos
);
656 static struct timeval
get_drm_timestamp(void)
660 now
= drm_timestamp_monotonic
? ktime_get() : ktime_get_real();
661 return ktime_to_timeval(now
);
665 * drm_get_last_vbltimestamp - retrieve raw timestamp for the most recent
668 * @crtc: which CRTC's vblank timestamp to retrieve
669 * @tvblank: Pointer to target struct timeval which should receive the timestamp
670 * @flags: Flags to pass to driver:
672 * DRM_CALLED_FROM_VBLIRQ = If function is called from vbl IRQ handler
674 * Fetches the system timestamp corresponding to the time of the most recent
675 * vblank interval on specified CRTC. May call into kms-driver to
676 * compute the timestamp with a high-precision GPU specific method.
678 * Returns zero if timestamp originates from uncorrected do_gettimeofday()
679 * call, i.e., it isn't very precisely locked to the true vblank.
682 * Non-zero if timestamp is considered to be very precise, zero otherwise.
684 u32
drm_get_last_vbltimestamp(struct drm_device
*dev
, int crtc
,
685 struct timeval
*tvblank
, unsigned flags
)
689 /* Define requested maximum error on timestamps (nanoseconds). */
690 int max_error
= (int) drm_timestamp_precision
* 1000;
692 /* Query driver if possible and precision timestamping enabled. */
693 if (dev
->driver
->get_vblank_timestamp
&& (max_error
> 0)) {
694 ret
= dev
->driver
->get_vblank_timestamp(dev
, crtc
, &max_error
,
700 /* GPU high precision timestamp query unsupported or failed.
701 * Return current monotonic/gettimeofday timestamp as best estimate.
703 *tvblank
= get_drm_timestamp();
707 EXPORT_SYMBOL(drm_get_last_vbltimestamp
);
710 * drm_vblank_count - retrieve "cooked" vblank counter value
712 * @crtc: which counter to retrieve
714 * Fetches the "cooked" vblank count value that represents the number of
715 * vblank events since the system was booted, including lost events due to
716 * modesetting activity.
719 * The software vblank counter.
721 u32
drm_vblank_count(struct drm_device
*dev
, int crtc
)
723 return atomic_read(&dev
->vblank
[crtc
].count
);
725 EXPORT_SYMBOL(drm_vblank_count
);
728 * drm_vblank_count_and_time - retrieve "cooked" vblank counter value
729 * and the system timestamp corresponding to that vblank counter value.
732 * @crtc: which counter to retrieve
733 * @vblanktime: Pointer to struct timeval to receive the vblank timestamp.
735 * Fetches the "cooked" vblank count value that represents the number of
736 * vblank events since the system was booted, including lost events due to
737 * modesetting activity. Returns corresponding system timestamp of the time
738 * of the vblank interval that corresponds to the current vblank counter value.
740 u32
drm_vblank_count_and_time(struct drm_device
*dev
, int crtc
,
741 struct timeval
*vblanktime
)
745 /* Read timestamp from slot of _vblank_time ringbuffer
746 * that corresponds to current vblank count. Retry if
747 * count has incremented during readout. This works like
751 cur_vblank
= atomic_read(&dev
->vblank
[crtc
].count
);
752 *vblanktime
= vblanktimestamp(dev
, crtc
, cur_vblank
);
754 } while (cur_vblank
!= atomic_read(&dev
->vblank
[crtc
].count
));
758 EXPORT_SYMBOL(drm_vblank_count_and_time
);
760 static void send_vblank_event(struct drm_device
*dev
,
761 struct drm_pending_vblank_event
*e
,
762 unsigned long seq
, struct timeval
*now
)
764 WARN_ON_SMP(!spin_is_locked(&dev
->event_lock
));
765 e
->event
.sequence
= seq
;
766 e
->event
.tv_sec
= now
->tv_sec
;
767 e
->event
.tv_usec
= now
->tv_usec
;
769 list_add_tail(&e
->base
.link
,
770 &e
->base
.file_priv
->event_list
);
771 wake_up_interruptible(&e
->base
.file_priv
->event_wait
);
772 trace_drm_vblank_event_delivered(e
->base
.pid
, e
->pipe
,
777 * drm_send_vblank_event - helper to send vblank event after pageflip
779 * @crtc: CRTC in question
780 * @e: the event to send
782 * Updates sequence # and timestamp on event, and sends it to userspace.
783 * Caller must hold event lock.
785 void drm_send_vblank_event(struct drm_device
*dev
, int crtc
,
786 struct drm_pending_vblank_event
*e
)
791 seq
= drm_vblank_count_and_time(dev
, crtc
, &now
);
795 now
= get_drm_timestamp();
798 send_vblank_event(dev
, e
, seq
, &now
);
800 EXPORT_SYMBOL(drm_send_vblank_event
);
803 * drm_update_vblank_count - update the master vblank counter
805 * @crtc: counter to update
807 * Call back into the driver to update the appropriate vblank counter
808 * (specified by @crtc). Deal with wraparound, if it occurred, and
809 * update the last read value so we can deal with wraparound on the next
812 * Only necessary when going from off->on, to account for frames we
813 * didn't get an interrupt for.
815 * Note: caller must hold dev->vbl_lock since this reads & writes
816 * device vblank fields.
818 static void drm_update_vblank_count(struct drm_device
*dev
, int crtc
)
820 u32 cur_vblank
, diff
, tslot
, rc
;
821 struct timeval t_vblank
;
824 * Interrupts were disabled prior to this call, so deal with counter
826 * NOTE! It's possible we lost a full dev->max_vblank_count events
827 * here if the register is small or we had vblank interrupts off for
830 * We repeat the hardware vblank counter & timestamp query until
831 * we get consistent results. This to prevent races between gpu
832 * updating its hardware counter while we are retrieving the
833 * corresponding vblank timestamp.
836 cur_vblank
= dev
->driver
->get_vblank_counter(dev
, crtc
);
837 rc
= drm_get_last_vbltimestamp(dev
, crtc
, &t_vblank
, 0);
838 } while (cur_vblank
!= dev
->driver
->get_vblank_counter(dev
, crtc
));
840 /* Deal with counter wrap */
841 diff
= cur_vblank
- dev
->vblank
[crtc
].last
;
842 if (cur_vblank
< dev
->vblank
[crtc
].last
) {
843 diff
+= dev
->max_vblank_count
;
845 DRM_DEBUG("last_vblank[%d]=0x%x, cur_vblank=0x%x => diff=0x%x\n",
846 crtc
, dev
->vblank
[crtc
].last
, cur_vblank
, diff
);
849 DRM_DEBUG("enabling vblank interrupts on crtc %d, missed %d\n",
852 /* Reinitialize corresponding vblank timestamp if high-precision query
853 * available. Skip this step if query unsupported or failed. Will
854 * reinitialize delayed at next vblank interrupt in that case.
857 tslot
= atomic_read(&dev
->vblank
[crtc
].count
) + diff
;
858 vblanktimestamp(dev
, crtc
, tslot
) = t_vblank
;
861 smp_mb__before_atomic();
862 atomic_add(diff
, &dev
->vblank
[crtc
].count
);
863 smp_mb__after_atomic();
867 * drm_vblank_enable - enable the vblank interrupt on a CRTC
869 * @crtc: CRTC in question
871 static int drm_vblank_enable(struct drm_device
*dev
, int crtc
)
875 assert_spin_locked(&dev
->vbl_lock
);
877 spin_lock(&dev
->vblank_time_lock
);
879 if (!dev
->vblank
[crtc
].enabled
) {
881 * Enable vblank irqs under vblank_time_lock protection.
882 * All vblank count & timestamp updates are held off
883 * until we are done reinitializing master counter and
884 * timestamps. Filtercode in drm_handle_vblank() will
885 * prevent double-accounting of same vblank interval.
887 ret
= dev
->driver
->enable_vblank(dev
, crtc
);
888 DRM_DEBUG("enabling vblank on crtc %d, ret: %d\n", crtc
, ret
);
890 atomic_dec(&dev
->vblank
[crtc
].refcount
);
892 dev
->vblank
[crtc
].enabled
= true;
893 drm_update_vblank_count(dev
, crtc
);
897 spin_unlock(&dev
->vblank_time_lock
);
903 * drm_vblank_get - get a reference count on vblank events
905 * @crtc: which CRTC to own
907 * Acquire a reference count on vblank events to avoid having them disabled
910 * This is the legacy version of drm_crtc_vblank_get().
913 * Zero on success, nonzero on failure.
915 int drm_vblank_get(struct drm_device
*dev
, int crtc
)
917 unsigned long irqflags
;
920 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
921 /* Going from 0->1 means we have to enable interrupts again */
922 if (atomic_add_return(1, &dev
->vblank
[crtc
].refcount
) == 1) {
923 ret
= drm_vblank_enable(dev
, crtc
);
925 if (!dev
->vblank
[crtc
].enabled
) {
926 atomic_dec(&dev
->vblank
[crtc
].refcount
);
930 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
934 EXPORT_SYMBOL(drm_vblank_get
);
937 * drm_crtc_vblank_get - get a reference count on vblank events
938 * @crtc: which CRTC to own
940 * Acquire a reference count on vblank events to avoid having them disabled
943 * This is the native kms version of drm_vblank_off().
946 * Zero on success, nonzero on failure.
948 int drm_crtc_vblank_get(struct drm_crtc
*crtc
)
950 return drm_vblank_get(crtc
->dev
, drm_crtc_index(crtc
));
952 EXPORT_SYMBOL(drm_crtc_vblank_get
);
955 * drm_vblank_put - give up ownership of vblank events
957 * @crtc: which counter to give up
959 * Release ownership of a given vblank counter, turning off interrupts
960 * if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
962 * This is the legacy version of drm_crtc_vblank_put().
964 void drm_vblank_put(struct drm_device
*dev
, int crtc
)
966 BUG_ON(atomic_read(&dev
->vblank
[crtc
].refcount
) == 0);
968 /* Last user schedules interrupt disable */
969 if (atomic_dec_and_test(&dev
->vblank
[crtc
].refcount
) &&
970 (drm_vblank_offdelay
> 0))
971 mod_timer(&dev
->vblank
[crtc
].disable_timer
,
972 jiffies
+ ((drm_vblank_offdelay
* HZ
)/1000));
974 EXPORT_SYMBOL(drm_vblank_put
);
977 * drm_crtc_vblank_put - give up ownership of vblank events
978 * @crtc: which counter to give up
980 * Release ownership of a given vblank counter, turning off interrupts
981 * if possible. Disable interrupts after drm_vblank_offdelay milliseconds.
983 * This is the native kms version of drm_vblank_put().
985 void drm_crtc_vblank_put(struct drm_crtc
*crtc
)
987 drm_vblank_put(crtc
->dev
, drm_crtc_index(crtc
));
989 EXPORT_SYMBOL(drm_crtc_vblank_put
);
992 * drm_vblank_off - disable vblank events on a CRTC
994 * @crtc: CRTC in question
996 * Drivers can use this function to shut down the vblank interrupt handling when
997 * disabling a crtc. This function ensures that the latest vblank frame count is
998 * stored so that drm_vblank_on() can restore it again.
1000 * Drivers must use this function when the hardware vblank counter can get
1001 * reset, e.g. when suspending.
1003 * This is the legacy version of drm_crtc_vblank_off().
1005 void drm_vblank_off(struct drm_device
*dev
, int crtc
)
1007 struct drm_pending_vblank_event
*e
, *t
;
1009 unsigned long irqflags
;
1012 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
1013 vblank_disable_and_save(dev
, crtc
);
1014 wake_up(&dev
->vblank
[crtc
].queue
);
1016 /* Send any queued vblank events, lest the natives grow disquiet */
1017 seq
= drm_vblank_count_and_time(dev
, crtc
, &now
);
1019 spin_lock(&dev
->event_lock
);
1020 list_for_each_entry_safe(e
, t
, &dev
->vblank_event_list
, base
.link
) {
1021 if (e
->pipe
!= crtc
)
1023 DRM_DEBUG("Sending premature vblank event on disable: \
1024 wanted %d, current %d\n",
1025 e
->event
.sequence
, seq
);
1026 list_del(&e
->base
.link
);
1027 drm_vblank_put(dev
, e
->pipe
);
1028 send_vblank_event(dev
, e
, seq
, &now
);
1030 spin_unlock(&dev
->event_lock
);
1032 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
1034 EXPORT_SYMBOL(drm_vblank_off
);
1037 * drm_crtc_vblank_off - disable vblank events on a CRTC
1038 * @crtc: CRTC in question
1040 * Drivers can use this function to shut down the vblank interrupt handling when
1041 * disabling a crtc. This function ensures that the latest vblank frame count is
1042 * stored so that drm_vblank_on can restore it again.
1044 * Drivers must use this function when the hardware vblank counter can get
1045 * reset, e.g. when suspending.
1047 * This is the native kms version of drm_vblank_off().
1049 void drm_crtc_vblank_off(struct drm_crtc
*crtc
)
1051 drm_vblank_off(crtc
->dev
, drm_crtc_index(crtc
));
1053 EXPORT_SYMBOL(drm_crtc_vblank_off
);
1056 * drm_vblank_on - enable vblank events on a CRTC
1058 * @crtc: CRTC in question
1060 * This functions restores the vblank interrupt state captured with
1061 * drm_vblank_off() again. Note that calls to drm_vblank_on() and
1062 * drm_vblank_off() can be unbalanced and so can also be unconditionaly called
1063 * in driver load code to reflect the current hardware state of the crtc.
1065 * This is the legacy version of drm_crtc_vblank_on().
1067 void drm_vblank_on(struct drm_device
*dev
, int crtc
)
1069 unsigned long irqflags
;
1071 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
1072 /* re-enable interrupts if there's are users left */
1073 if (atomic_read(&dev
->vblank
[crtc
].refcount
) != 0)
1074 WARN_ON(drm_vblank_enable(dev
, crtc
));
1075 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
1077 EXPORT_SYMBOL(drm_vblank_on
);
1080 * drm_crtc_vblank_on - enable vblank events on a CRTC
1081 * @crtc: CRTC in question
1083 * This functions restores the vblank interrupt state captured with
1084 * drm_vblank_off() again. Note that calls to drm_vblank_on() and
1085 * drm_vblank_off() can be unbalanced and so can also be unconditionaly called
1086 * in driver load code to reflect the current hardware state of the crtc.
1088 * This is the native kms version of drm_vblank_on().
1090 void drm_crtc_vblank_on(struct drm_crtc
*crtc
)
1092 drm_vblank_on(crtc
->dev
, drm_crtc_index(crtc
));
1094 EXPORT_SYMBOL(drm_crtc_vblank_on
);
1097 * drm_vblank_pre_modeset - account for vblanks across mode sets
1099 * @crtc: CRTC in question
1101 * Account for vblank events across mode setting events, which will likely
1102 * reset the hardware frame counter.
1104 * This is done by grabbing a temporary vblank reference to ensure that the
1105 * vblank interrupt keeps running across the modeset sequence. With this the
1106 * software-side vblank frame counting will ensure that there are no jumps or
1109 * Unfortunately this approach is racy and also doesn't work when the vblank
1110 * interrupt stops running, e.g. across system suspend resume. It is therefore
1111 * highly recommended that drivers use the newer drm_vblank_off() and
1112 * drm_vblank_on() instead. drm_vblank_pre_modeset() only works correctly when
1113 * using "cooked" software vblank frame counters and not relying on any hardware
1116 * Drivers must call drm_vblank_post_modeset() when re-enabling the same crtc
1119 void drm_vblank_pre_modeset(struct drm_device
*dev
, int crtc
)
1121 /* vblank is not initialized (IRQ not installed ?), or has been freed */
1122 if (!dev
->num_crtcs
)
1125 * To avoid all the problems that might happen if interrupts
1126 * were enabled/disabled around or between these calls, we just
1127 * have the kernel take a reference on the CRTC (just once though
1128 * to avoid corrupting the count if multiple, mismatch calls occur),
1129 * so that interrupts remain enabled in the interim.
1131 if (!dev
->vblank
[crtc
].inmodeset
) {
1132 dev
->vblank
[crtc
].inmodeset
= 0x1;
1133 if (drm_vblank_get(dev
, crtc
) == 0)
1134 dev
->vblank
[crtc
].inmodeset
|= 0x2;
1137 EXPORT_SYMBOL(drm_vblank_pre_modeset
);
1140 * drm_vblank_post_modeset - undo drm_vblank_pre_modeset changes
1142 * @crtc: CRTC in question
1144 * This function again drops the temporary vblank reference acquired in
1145 * drm_vblank_pre_modeset.
1147 void drm_vblank_post_modeset(struct drm_device
*dev
, int crtc
)
1149 unsigned long irqflags
;
1151 /* vblank is not initialized (IRQ not installed ?), or has been freed */
1152 if (!dev
->num_crtcs
)
1155 if (dev
->vblank
[crtc
].inmodeset
) {
1156 spin_lock_irqsave(&dev
->vbl_lock
, irqflags
);
1157 dev
->vblank_disable_allowed
= true;
1158 spin_unlock_irqrestore(&dev
->vbl_lock
, irqflags
);
1160 if (dev
->vblank
[crtc
].inmodeset
& 0x2)
1161 drm_vblank_put(dev
, crtc
);
1163 dev
->vblank
[crtc
].inmodeset
= 0;
1166 EXPORT_SYMBOL(drm_vblank_post_modeset
);
1169 * drm_modeset_ctl - handle vblank event counter changes across mode switch
1170 * @DRM_IOCTL_ARGS: standard ioctl arguments
1172 * Applications should call the %_DRM_PRE_MODESET and %_DRM_POST_MODESET
1173 * ioctls around modesetting so that any lost vblank events are accounted for.
1175 * Generally the counter will reset across mode sets. If interrupts are
1176 * enabled around this call, we don't have to do anything since the counter
1177 * will have already been incremented.
1179 int drm_modeset_ctl(struct drm_device
*dev
, void *data
,
1180 struct drm_file
*file_priv
)
1182 struct drm_modeset_ctl
*modeset
= data
;
1185 /* If drm_vblank_init() hasn't been called yet, just no-op */
1186 if (!dev
->num_crtcs
)
1189 /* KMS drivers handle this internally */
1190 if (drm_core_check_feature(dev
, DRIVER_MODESET
))
1193 crtc
= modeset
->crtc
;
1194 if (crtc
>= dev
->num_crtcs
)
1197 switch (modeset
->cmd
) {
1198 case _DRM_PRE_MODESET
:
1199 drm_vblank_pre_modeset(dev
, crtc
);
1201 case _DRM_POST_MODESET
:
1202 drm_vblank_post_modeset(dev
, crtc
);
1211 static int drm_queue_vblank_event(struct drm_device
*dev
, int pipe
,
1212 union drm_wait_vblank
*vblwait
,
1213 struct drm_file
*file_priv
)
1215 struct drm_pending_vblank_event
*e
;
1217 unsigned long flags
;
1221 e
= kzalloc(sizeof *e
, GFP_KERNEL
);
1228 e
->base
.pid
= current
->pid
;
1229 e
->event
.base
.type
= DRM_EVENT_VBLANK
;
1230 e
->event
.base
.length
= sizeof e
->event
;
1231 e
->event
.user_data
= vblwait
->request
.signal
;
1232 e
->base
.event
= &e
->event
.base
;
1233 e
->base
.file_priv
= file_priv
;
1234 e
->base
.destroy
= (void (*) (struct drm_pending_event
*)) kfree
;
1236 spin_lock_irqsave(&dev
->event_lock
, flags
);
1238 if (file_priv
->event_space
< sizeof e
->event
) {
1243 file_priv
->event_space
-= sizeof e
->event
;
1244 seq
= drm_vblank_count_and_time(dev
, pipe
, &now
);
1246 if ((vblwait
->request
.type
& _DRM_VBLANK_NEXTONMISS
) &&
1247 (seq
- vblwait
->request
.sequence
) <= (1 << 23)) {
1248 vblwait
->request
.sequence
= seq
+ 1;
1249 vblwait
->reply
.sequence
= vblwait
->request
.sequence
;
1252 DRM_DEBUG("event on vblank count %d, current %d, crtc %d\n",
1253 vblwait
->request
.sequence
, seq
, pipe
);
1255 trace_drm_vblank_event_queued(current
->pid
, pipe
,
1256 vblwait
->request
.sequence
);
1258 e
->event
.sequence
= vblwait
->request
.sequence
;
1259 if ((seq
- vblwait
->request
.sequence
) <= (1 << 23)) {
1260 drm_vblank_put(dev
, pipe
);
1261 send_vblank_event(dev
, e
, seq
, &now
);
1262 vblwait
->reply
.sequence
= seq
;
1264 /* drm_handle_vblank_events will call drm_vblank_put */
1265 list_add_tail(&e
->base
.link
, &dev
->vblank_event_list
);
1266 vblwait
->reply
.sequence
= vblwait
->request
.sequence
;
1269 spin_unlock_irqrestore(&dev
->event_lock
, flags
);
1274 spin_unlock_irqrestore(&dev
->event_lock
, flags
);
1277 drm_vblank_put(dev
, pipe
);
1284 * \param inode device inode.
1285 * \param file_priv DRM file private.
1286 * \param cmd command.
1287 * \param data user argument, pointing to a drm_wait_vblank structure.
1288 * \return zero on success or a negative number on failure.
1290 * This function enables the vblank interrupt on the pipe requested, then
1291 * sleeps waiting for the requested sequence number to occur, and drops
1292 * the vblank interrupt refcount afterwards. (vblank IRQ disable follows that
1293 * after a timeout with no further vblank waits scheduled).
1295 int drm_wait_vblank(struct drm_device
*dev
, void *data
,
1296 struct drm_file
*file_priv
)
1298 union drm_wait_vblank
*vblwait
= data
;
1300 unsigned int flags
, seq
, crtc
, high_crtc
;
1302 if (!dev
->irq_enabled
)
1305 if (vblwait
->request
.type
& _DRM_VBLANK_SIGNAL
)
1308 if (vblwait
->request
.type
&
1309 ~(_DRM_VBLANK_TYPES_MASK
| _DRM_VBLANK_FLAGS_MASK
|
1310 _DRM_VBLANK_HIGH_CRTC_MASK
)) {
1311 DRM_ERROR("Unsupported type value 0x%x, supported mask 0x%x\n",
1312 vblwait
->request
.type
,
1313 (_DRM_VBLANK_TYPES_MASK
| _DRM_VBLANK_FLAGS_MASK
|
1314 _DRM_VBLANK_HIGH_CRTC_MASK
));
1318 flags
= vblwait
->request
.type
& _DRM_VBLANK_FLAGS_MASK
;
1319 high_crtc
= (vblwait
->request
.type
& _DRM_VBLANK_HIGH_CRTC_MASK
);
1321 crtc
= high_crtc
>> _DRM_VBLANK_HIGH_CRTC_SHIFT
;
1323 crtc
= flags
& _DRM_VBLANK_SECONDARY
? 1 : 0;
1324 if (crtc
>= dev
->num_crtcs
)
1327 ret
= drm_vblank_get(dev
, crtc
);
1329 DRM_DEBUG("failed to acquire vblank counter, %d\n", ret
);
1332 seq
= drm_vblank_count(dev
, crtc
);
1334 switch (vblwait
->request
.type
& _DRM_VBLANK_TYPES_MASK
) {
1335 case _DRM_VBLANK_RELATIVE
:
1336 vblwait
->request
.sequence
+= seq
;
1337 vblwait
->request
.type
&= ~_DRM_VBLANK_RELATIVE
;
1338 case _DRM_VBLANK_ABSOLUTE
:
1345 if (flags
& _DRM_VBLANK_EVENT
) {
1346 /* must hold on to the vblank ref until the event fires
1347 * drm_vblank_put will be called asynchronously
1349 return drm_queue_vblank_event(dev
, crtc
, vblwait
, file_priv
);
1352 if ((flags
& _DRM_VBLANK_NEXTONMISS
) &&
1353 (seq
- vblwait
->request
.sequence
) <= (1<<23)) {
1354 vblwait
->request
.sequence
= seq
+ 1;
1357 DRM_DEBUG("waiting on vblank count %d, crtc %d\n",
1358 vblwait
->request
.sequence
, crtc
);
1359 dev
->vblank
[crtc
].last_wait
= vblwait
->request
.sequence
;
1360 DRM_WAIT_ON(ret
, dev
->vblank
[crtc
].queue
, 3 * HZ
,
1361 (((drm_vblank_count(dev
, crtc
) -
1362 vblwait
->request
.sequence
) <= (1 << 23)) ||
1363 !dev
->vblank
[crtc
].enabled
||
1364 !dev
->irq_enabled
));
1366 if (ret
!= -EINTR
) {
1369 vblwait
->reply
.sequence
= drm_vblank_count_and_time(dev
, crtc
, &now
);
1370 vblwait
->reply
.tval_sec
= now
.tv_sec
;
1371 vblwait
->reply
.tval_usec
= now
.tv_usec
;
1373 DRM_DEBUG("returning %d to client\n",
1374 vblwait
->reply
.sequence
);
1376 DRM_DEBUG("vblank wait interrupted by signal\n");
1380 drm_vblank_put(dev
, crtc
);
1384 static void drm_handle_vblank_events(struct drm_device
*dev
, int crtc
)
1386 struct drm_pending_vblank_event
*e
, *t
;
1388 unsigned long flags
;
1391 seq
= drm_vblank_count_and_time(dev
, crtc
, &now
);
1393 spin_lock_irqsave(&dev
->event_lock
, flags
);
1395 list_for_each_entry_safe(e
, t
, &dev
->vblank_event_list
, base
.link
) {
1396 if (e
->pipe
!= crtc
)
1398 if ((seq
- e
->event
.sequence
) > (1<<23))
1401 DRM_DEBUG("vblank event on %d, current %d\n",
1402 e
->event
.sequence
, seq
);
1404 list_del(&e
->base
.link
);
1405 drm_vblank_put(dev
, e
->pipe
);
1406 send_vblank_event(dev
, e
, seq
, &now
);
1409 spin_unlock_irqrestore(&dev
->event_lock
, flags
);
1411 trace_drm_vblank_event(crtc
, seq
);
1415 * drm_handle_vblank - handle a vblank event
1417 * @crtc: where this event occurred
1419 * Drivers should call this routine in their vblank interrupt handlers to
1420 * update the vblank counter and send any signals that may be pending.
1422 bool drm_handle_vblank(struct drm_device
*dev
, int crtc
)
1426 struct timeval tvblank
;
1427 unsigned long irqflags
;
1429 if (!dev
->num_crtcs
)
1432 /* Need timestamp lock to prevent concurrent execution with
1433 * vblank enable/disable, as this would cause inconsistent
1434 * or corrupted timestamps and vblank counts.
1436 spin_lock_irqsave(&dev
->vblank_time_lock
, irqflags
);
1438 /* Vblank irq handling disabled. Nothing to do. */
1439 if (!dev
->vblank
[crtc
].enabled
) {
1440 spin_unlock_irqrestore(&dev
->vblank_time_lock
, irqflags
);
1444 /* Fetch corresponding timestamp for this vblank interval from
1445 * driver and store it in proper slot of timestamp ringbuffer.
1448 /* Get current timestamp and count. */
1449 vblcount
= atomic_read(&dev
->vblank
[crtc
].count
);
1450 drm_get_last_vbltimestamp(dev
, crtc
, &tvblank
, DRM_CALLED_FROM_VBLIRQ
);
1452 /* Compute time difference to timestamp of last vblank */
1453 diff_ns
= timeval_to_ns(&tvblank
) -
1454 timeval_to_ns(&vblanktimestamp(dev
, crtc
, vblcount
));
1456 /* Update vblank timestamp and count if at least
1457 * DRM_REDUNDANT_VBLIRQ_THRESH_NS nanoseconds
1458 * difference between last stored timestamp and current
1459 * timestamp. A smaller difference means basically
1460 * identical timestamps. Happens if this vblank has
1461 * been already processed and this is a redundant call,
1462 * e.g., due to spurious vblank interrupts. We need to
1463 * ignore those for accounting.
1465 if (abs64(diff_ns
) > DRM_REDUNDANT_VBLIRQ_THRESH_NS
) {
1466 /* Store new timestamp in ringbuffer. */
1467 vblanktimestamp(dev
, crtc
, vblcount
+ 1) = tvblank
;
1469 /* Increment cooked vblank count. This also atomically commits
1470 * the timestamp computed above.
1472 smp_mb__before_atomic();
1473 atomic_inc(&dev
->vblank
[crtc
].count
);
1474 smp_mb__after_atomic();
1476 DRM_DEBUG("crtc %d: Redundant vblirq ignored. diff_ns = %d\n",
1477 crtc
, (int) diff_ns
);
1480 wake_up(&dev
->vblank
[crtc
].queue
);
1481 drm_handle_vblank_events(dev
, crtc
);
1483 spin_unlock_irqrestore(&dev
->vblank_time_lock
, irqflags
);
1486 EXPORT_SYMBOL(drm_handle_vblank
);