drivers/gpu/drm/i915/intel_hdmi.c

   1 /*
   2  * Copyright 2006 Dave Airlie <airlied@linux.ie>
   3  * Copyright © 2006-2009 Intel Corporation
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22  * DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *      Eric Anholt <eric@anholt.net>
  26  *      Jesse Barnes <jesse.barnes@intel.com>
  27  */
  28
  29 #include <linux/i2c.h>
  30 #include <linux/slab.h>
  31 #include <linux/delay.h>
  32 #include "drmP.h"
  33 #include "drm.h"
  34 #include "drm_crtc.h"
  35 #include "drm_edid.h"
  36 #include "intel_drv.h"
  37 #include "i915_drm.h"
  38 #include "i915_drv.h"
  39
  40 struct intel_hdmi {
  41         struct intel_encoder base;
  42         u32 sdvox_reg;
  43         int ddc_bus;
  44         uint32_t color_range;
  45         bool has_hdmi_sink;
  46         bool has_audio;
  47         enum hdmi_force_audio force_audio;
  48         void (*write_infoframe)(struct drm_encoder *encoder,
  49                                 struct dip_infoframe *frame);
  50 };
  51
  52 static struct intel_hdmi *enc_to_intel_hdmi(struct drm_encoder *encoder)
  53 {
  54         return container_of(encoder, struct intel_hdmi, base.base);
  55 }
  56
  57 static struct intel_hdmi *intel_attached_hdmi(struct drm_connector *connector)
  58 {
  59         return container_of(intel_attached_encoder(connector),
  60                             struct intel_hdmi, base);
  61 }
  62
  63 void intel_dip_infoframe_csum(struct dip_infoframe *frame)
  64 {
  65         uint8_t *data = (uint8_t *)frame;
  66         uint8_t sum = 0;
  67         unsigned i;
  68
  69         frame->checksum = 0;
  70         frame->ecc = 0;
  71
  72         for (i = 0; i < frame->len + DIP_HEADER_SIZE; i++)
  73                 sum += data[i];
  74
  75         frame->checksum = 0x100 - sum;
  76 }
  77
  78 static u32 intel_infoframe_index(struct dip_infoframe *frame)
  79 {
  80         u32 flags = 0;
  81
  82         switch (frame->type) {
  83         case DIP_TYPE_AVI:
  84                 flags |= VIDEO_DIP_SELECT_AVI;
  85                 break;
  86         case DIP_TYPE_SPD:
  87                 flags |= VIDEO_DIP_SELECT_SPD;
  88                 break;
  89         default:
  90                 DRM_DEBUG_DRIVER("unknown info frame type %d\n", frame->type);
  91                 break;
  92         }
  93
  94         return flags;
  95 }
  96
  97 static u32 intel_infoframe_flags(struct dip_infoframe *frame)
  98 {
  99         u32 flags = 0;
 100
 101         switch (frame->type) {
 102         case DIP_TYPE_AVI:
 103                 flags |= VIDEO_DIP_ENABLE_AVI | VIDEO_DIP_FREQ_VSYNC;
 104                 break;
 105         case DIP_TYPE_SPD:
 106                 flags |= VIDEO_DIP_ENABLE_SPD | VIDEO_DIP_FREQ_VSYNC;
 107                 break;
 108         default:
 109                 DRM_DEBUG_DRIVER("unknown info frame type %d\n", frame->type);
 110                 break;
 111         }
 112
 113         return flags;
 114 }
 115
 116 static void i9xx_write_infoframe(struct drm_encoder *encoder,
 117                                  struct dip_infoframe *frame)
 118 {
 119         uint32_t *data = (uint32_t *)frame;
 120         struct drm_device *dev = encoder->dev;
 121         struct drm_i915_private *dev_priv = dev->dev_private;
 122         struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 123         u32 port, flags, val = I915_READ(VIDEO_DIP_CTL);
 124         unsigned i, len = DIP_HEADER_SIZE + frame->len;
 125
 126
 127         /* XXX first guess at handling video port, is this corrent? */
 128         if (intel_hdmi->sdvox_reg == SDVOB)
 129                 port = VIDEO_DIP_PORT_B;
 130         else if (intel_hdmi->sdvox_reg == SDVOC)
 131                 port = VIDEO_DIP_PORT_C;
 132         else
 133                 return;
 134
 135         flags = intel_infoframe_index(frame);
 136
 137         val &= ~VIDEO_DIP_SELECT_MASK;
 138
 139         I915_WRITE(VIDEO_DIP_CTL, VIDEO_DIP_ENABLE | val | port | flags);
 140
 141         for (i = 0; i < len; i += 4) {
 142                 I915_WRITE(VIDEO_DIP_DATA, *data);
 143                 data++;
 144         }
 145
 146         flags |= intel_infoframe_flags(frame);
 147
 148         I915_WRITE(VIDEO_DIP_CTL, VIDEO_DIP_ENABLE | val | port | flags);
 149 }
 150
 151 static void ironlake_write_infoframe(struct drm_encoder *encoder,
 152                                      struct dip_infoframe *frame)
 153 {
 154         uint32_t *data = (uint32_t *)frame;
 155         struct drm_device *dev = encoder->dev;
 156         struct drm_i915_private *dev_priv = dev->dev_private;
 157         struct drm_crtc *crtc = encoder->crtc;
 158         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 159         int reg = TVIDEO_DIP_CTL(intel_crtc->pipe);
 160         unsigned i, len = DIP_HEADER_SIZE + frame->len;
 161         u32 flags, val = I915_READ(reg);
 162
 163         intel_wait_for_vblank(dev, intel_crtc->pipe);
 164
 165         flags = intel_infoframe_index(frame);
 166
 167         val &= ~(VIDEO_DIP_SELECT_MASK | 0xf); /* clear DIP data offset */
 168
 169         I915_WRITE(reg, VIDEO_DIP_ENABLE | val | flags);
 170
 171         for (i = 0; i < len; i += 4) {
 172                 I915_WRITE(TVIDEO_DIP_DATA(intel_crtc->pipe), *data);
 173                 data++;
 174         }
 175
 176         flags |= intel_infoframe_flags(frame);
 177
 178         I915_WRITE(reg, VIDEO_DIP_ENABLE | val | flags);
 179 }
 180 static void intel_set_infoframe(struct drm_encoder *encoder,
 181                                 struct dip_infoframe *frame)
 182 {
 183         struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 184
 185         if (!intel_hdmi->has_hdmi_sink)
 186                 return;
 187
 188         intel_dip_infoframe_csum(frame);
 189         intel_hdmi->write_infoframe(encoder, frame);
 190 }
 191
 192 static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder)
 193 {
 194         struct dip_infoframe avi_if = {
 195                 .type = DIP_TYPE_AVI,
 196                 .ver = DIP_VERSION_AVI,
 197                 .len = DIP_LEN_AVI,
 198         };
 199
 200         intel_set_infoframe(encoder, &avi_if);
 201 }
 202
 203 static void intel_hdmi_set_spd_infoframe(struct drm_encoder *encoder)
 204 {
 205         struct dip_infoframe spd_if;
 206
 207         memset(&spd_if, 0, sizeof(spd_if));
 208         spd_if.type = DIP_TYPE_SPD;
 209         spd_if.ver = DIP_VERSION_SPD;
 210         spd_if.len = DIP_LEN_SPD;
 211         strcpy(spd_if.body.spd.vn, "Intel");
 212         strcpy(spd_if.body.spd.pd, "Integrated gfx");
 213         spd_if.body.spd.sdi = DIP_SPD_PC;
 214
 215         intel_set_infoframe(encoder, &spd_if);
 216 }
 217
 218 static void intel_hdmi_mode_set(struct drm_encoder *encoder,
 219                                 struct drm_display_mode *mode,
 220                                 struct drm_display_mode *adjusted_mode)
 221 {
 222         struct drm_device *dev = encoder->dev;
 223         struct drm_i915_private *dev_priv = dev->dev_private;
 224         struct drm_crtc *crtc = encoder->crtc;
 225         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
 226         struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 227         u32 sdvox;
 228
 229         sdvox = SDVO_ENCODING_HDMI | SDVO_BORDER_ENABLE;
 230         if (!HAS_PCH_SPLIT(dev))
 231                 sdvox |= intel_hdmi->color_range;
 232         if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
 233                 sdvox |= SDVO_VSYNC_ACTIVE_HIGH;
 234         if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
 235                 sdvox |= SDVO_HSYNC_ACTIVE_HIGH;
 236
 237         if (intel_crtc->bpp > 24)
 238                 sdvox |= COLOR_FORMAT_12bpc;
 239         else
 240                 sdvox |= COLOR_FORMAT_8bpc;
 241
 242         /* Required on CPT */
 243         if (intel_hdmi->has_hdmi_sink && HAS_PCH_CPT(dev))
 244                 sdvox |= HDMI_MODE_SELECT;
 245
 246         if (intel_hdmi->has_audio) {
 247                 DRM_DEBUG_DRIVER("Enabling HDMI audio on pipe %c\n",
 248                                  pipe_name(intel_crtc->pipe));
 249                 sdvox |= SDVO_AUDIO_ENABLE;
 250                 sdvox |= SDVO_NULL_PACKETS_DURING_VSYNC;
 251                 intel_write_eld(encoder, adjusted_mode);
 252         }
 253
 254         if (HAS_PCH_CPT(dev))
 255                 sdvox |= PORT_TRANS_SEL_CPT(intel_crtc->pipe);
 256         else if (intel_crtc->pipe == 1)
 257                 sdvox |= SDVO_PIPE_B_SELECT;
 258
 259         I915_WRITE(intel_hdmi->sdvox_reg, sdvox);
 260         POSTING_READ(intel_hdmi->sdvox_reg);
 261
 262         intel_hdmi_set_avi_infoframe(encoder);
 263         intel_hdmi_set_spd_infoframe(encoder);
 264 }
 265
 266 static void intel_hdmi_dpms(struct drm_encoder *encoder, int mode)
 267 {
 268         struct drm_device *dev = encoder->dev;
 269         struct drm_i915_private *dev_priv = dev->dev_private;
 270         struct intel_hdmi *intel_hdmi = enc_to_intel_hdmi(encoder);
 271         u32 temp;
 272         u32 enable_bits = SDVO_ENABLE;
 273
 274         if (intel_hdmi->has_audio)
 275                 enable_bits |= SDVO_AUDIO_ENABLE;
 276
 277         temp = I915_READ(intel_hdmi->sdvox_reg);
 278
 279         /* HW workaround, need to toggle enable bit off and on for 12bpc, but
 280          * we do this anyway which shows more stable in testing.
 281          */
 282         if (HAS_PCH_SPLIT(dev)) {
 283                 I915_WRITE(intel_hdmi->sdvox_reg, temp & ~SDVO_ENABLE);
 284                 POSTING_READ(intel_hdmi->sdvox_reg);
 285         }
 286
 287         if (mode != DRM_MODE_DPMS_ON) {
 288                 temp &= ~enable_bits;
 289         } else {
 290                 temp |= enable_bits;
 291         }
 292
 293         I915_WRITE(intel_hdmi->sdvox_reg, temp);
 294         POSTING_READ(intel_hdmi->sdvox_reg);
 295
 296         /* HW workaround, need to write this twice for issue that may result
 297          * in first write getting masked.
 298          */
 299         if (HAS_PCH_SPLIT(dev)) {
 300                 I915_WRITE(intel_hdmi->sdvox_reg, temp);
 301                 POSTING_READ(intel_hdmi->sdvox_reg);
 302         }
 303 }
 304
 305 static int intel_hdmi_mode_valid(struct drm_connector *connector,
 306                                  struct drm_display_mode *mode)
 307 {
 308         if (mode->clock > 165000)
 309                 return MODE_CLOCK_HIGH;
 310         if (mode->clock < 20000)
 311                 return MODE_CLOCK_LOW;
 312
 313         if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
 314                 return MODE_NO_DBLESCAN;
 315
 316         return MODE_OK;
 317 }
 318
 319 static bool intel_hdmi_mode_fixup(struct drm_encoder *encoder,
 320                                   struct drm_display_mode *mode,
 321                                   struct drm_display_mode *adjusted_mode)
 322 {
 323         return true;
 324 }
 325
 326 static enum drm_connector_status
 327 intel_hdmi_detect(struct drm_connector *connector, bool force)
 328 {
 329         struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 330         struct drm_i915_private *dev_priv = connector->dev->dev_private;
 331         struct edid *edid;
 332         enum drm_connector_status status = connector_status_disconnected;
 333
 334         intel_hdmi->has_hdmi_sink = false;
 335         intel_hdmi->has_audio = false;
 336         edid = drm_get_edid(connector,
 337                             &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
 338
 339         if (edid) {
 340                 if (edid->input & DRM_EDID_INPUT_DIGITAL) {
 341                         status = connector_status_connected;
 342                         if (intel_hdmi->force_audio != HDMI_AUDIO_OFF_DVI)
 343                                 intel_hdmi->has_hdmi_sink =
 344                                                 drm_detect_hdmi_monitor(edid);
 345                         intel_hdmi->has_audio = drm_detect_monitor_audio(edid);
 346                 }
 347                 connector->display_info.raw_edid = NULL;
 348                 kfree(edid);
 349         }
 350
 351         if (status == connector_status_connected) {
 352                 if (intel_hdmi->force_audio != HDMI_AUDIO_AUTO)
 353                         intel_hdmi->has_audio =
 354                                 (intel_hdmi->force_audio == HDMI_AUDIO_ON);
 355         }
 356
 357         return status;
 358 }
 359
 360 static int intel_hdmi_get_modes(struct drm_connector *connector)
 361 {
 362         struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 363         struct drm_i915_private *dev_priv = connector->dev->dev_private;
 364
 365         /* We should parse the EDID data and find out if it's an HDMI sink so
 366          * we can send audio to it.
 367          */
 368
 369         return intel_ddc_get_modes(connector,
 370                                    &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
 371 }
 372
 373 static bool
 374 intel_hdmi_detect_audio(struct drm_connector *connector)
 375 {
 376         struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 377         struct drm_i915_private *dev_priv = connector->dev->dev_private;
 378         struct edid *edid;
 379         bool has_audio = false;
 380
 381         edid = drm_get_edid(connector,
 382                             &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
 383         if (edid) {
 384                 if (edid->input & DRM_EDID_INPUT_DIGITAL)
 385                         has_audio = drm_detect_monitor_audio(edid);
 386
 387                 connector->display_info.raw_edid = NULL;
 388                 kfree(edid);
 389         }
 390
 391         return has_audio;
 392 }
 393
 394 static int
 395 intel_hdmi_set_property(struct drm_connector *connector,
 396                       struct drm_property *property,
 397                       uint64_t val)
 398 {
 399         struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
 400         struct drm_i915_private *dev_priv = connector->dev->dev_private;
 401         int ret;
 402
 403         ret = drm_connector_property_set_value(connector, property, val);
 404         if (ret)
 405                 return ret;
 406
 407         if (property == dev_priv->force_audio_property) {
 408                 enum hdmi_force_audio i = val;
 409                 bool has_audio;
 410
 411                 if (i == intel_hdmi->force_audio)
 412                         return 0;
 413
 414                 intel_hdmi->force_audio = i;
 415
 416                 if (i == HDMI_AUDIO_AUTO)
 417                         has_audio = intel_hdmi_detect_audio(connector);
 418                 else
 419                         has_audio = (i == HDMI_AUDIO_ON);
 420
 421                 if (i == HDMI_AUDIO_OFF_DVI)
 422                         intel_hdmi->has_hdmi_sink = 0;
 423
 424                 intel_hdmi->has_audio = has_audio;
 425                 goto done;
 426         }
 427
 428         if (property == dev_priv->broadcast_rgb_property) {
 429                 if (val == !!intel_hdmi->color_range)
 430                         return 0;
 431
 432                 intel_hdmi->color_range = val ? SDVO_COLOR_RANGE_16_235 : 0;
 433                 goto done;
 434         }
 435
 436         return -EINVAL;
 437
 438 done:
 439         if (intel_hdmi->base.base.crtc) {
 440                 struct drm_crtc *crtc = intel_hdmi->base.base.crtc;
 441                 drm_crtc_helper_set_mode(crtc, &crtc->mode,
 442                                          crtc->x, crtc->y,
 443                                          crtc->fb);
 444         }
 445
 446         return 0;
 447 }
 448
 449 static void intel_hdmi_destroy(struct drm_connector *connector)
 450 {
 451         drm_sysfs_connector_remove(connector);
 452         drm_connector_cleanup(connector);
 453         kfree(connector);
 454 }
 455
 456 static const struct drm_encoder_helper_funcs intel_hdmi_helper_funcs = {
 457         .dpms = intel_hdmi_dpms,
 458         .mode_fixup = intel_hdmi_mode_fixup,
 459         .prepare = intel_encoder_prepare,
 460         .mode_set = intel_hdmi_mode_set,
 461         .commit = intel_encoder_commit,
 462 };
 463
 464 static const struct drm_connector_funcs intel_hdmi_connector_funcs = {
 465         .dpms = drm_helper_connector_dpms,
 466         .detect = intel_hdmi_detect,
 467         .fill_modes = drm_helper_probe_single_connector_modes,
 468         .set_property = intel_hdmi_set_property,
 469         .destroy = intel_hdmi_destroy,
 470 };
 471
 472 static const struct drm_connector_helper_funcs intel_hdmi_connector_helper_funcs = {
 473         .get_modes = intel_hdmi_get_modes,
 474         .mode_valid = intel_hdmi_mode_valid,
 475         .best_encoder = intel_best_encoder,
 476 };
 477
 478 static const struct drm_encoder_funcs intel_hdmi_enc_funcs = {
 479         .destroy = intel_encoder_destroy,
 480 };
 481
 482 static void
 483 intel_hdmi_add_properties(struct intel_hdmi *intel_hdmi, struct drm_connector *connector)
 484 {
 485         intel_attach_force_audio_property(connector);
 486         intel_attach_broadcast_rgb_property(connector);
 487 }
 488
 489 void intel_hdmi_init(struct drm_device *dev, int sdvox_reg)
 490 {
 491         struct drm_i915_private *dev_priv = dev->dev_private;
 492         struct drm_connector *connector;
 493         struct intel_encoder *intel_encoder;
 494         struct intel_connector *intel_connector;
 495         struct intel_hdmi *intel_hdmi;
 496         int i;
 497
 498         intel_hdmi = kzalloc(sizeof(struct intel_hdmi), GFP_KERNEL);
 499         if (!intel_hdmi)
 500                 return;
 501
 502         intel_connector = kzalloc(sizeof(struct intel_connector), GFP_KERNEL);
 503         if (!intel_connector) {
 504                 kfree(intel_hdmi);
 505                 return;
 506         }
 507
 508         intel_encoder = &intel_hdmi->base;
 509         drm_encoder_init(dev, &intel_encoder->base, &intel_hdmi_enc_funcs,
 510                          DRM_MODE_ENCODER_TMDS);
 511
 512         connector = &intel_connector->base;
 513         drm_connector_init(dev, connector, &intel_hdmi_connector_funcs,
 514                            DRM_MODE_CONNECTOR_HDMIA);
 515         drm_connector_helper_add(connector, &intel_hdmi_connector_helper_funcs);
 516
 517         intel_encoder->type = INTEL_OUTPUT_HDMI;
 518
 519         connector->polled = DRM_CONNECTOR_POLL_HPD;
 520         connector->interlace_allowed = 1;
 521         connector->doublescan_allowed = 0;
 522         intel_encoder->crtc_mask = (1 << 0) | (1 << 1) | (1 << 2);
 523
 524         /* Set up the DDC bus. */
 525         if (sdvox_reg == SDVOB) {
 526                 intel_encoder->clone_mask = (1 << INTEL_HDMIB_CLONE_BIT);
 527                 intel_hdmi->ddc_bus = GMBUS_PORT_DPB;
 528                 dev_priv->hotplug_supported_mask |= HDMIB_HOTPLUG_INT_STATUS;
 529         } else if (sdvox_reg == SDVOC) {
 530                 intel_encoder->clone_mask = (1 << INTEL_HDMIC_CLONE_BIT);
 531                 intel_hdmi->ddc_bus = GMBUS_PORT_DPC;
 532                 dev_priv->hotplug_supported_mask |= HDMIC_HOTPLUG_INT_STATUS;
 533         } else if (sdvox_reg == HDMIB) {
 534                 intel_encoder->clone_mask = (1 << INTEL_HDMID_CLONE_BIT);
 535                 intel_hdmi->ddc_bus = GMBUS_PORT_DPB;
 536                 dev_priv->hotplug_supported_mask |= HDMIB_HOTPLUG_INT_STATUS;
 537         } else if (sdvox_reg == HDMIC) {
 538                 intel_encoder->clone_mask = (1 << INTEL_HDMIE_CLONE_BIT);
 539                 intel_hdmi->ddc_bus = GMBUS_PORT_DPC;
 540                 dev_priv->hotplug_supported_mask |= HDMIC_HOTPLUG_INT_STATUS;
 541         } else if (sdvox_reg == HDMID) {
 542                 intel_encoder->clone_mask = (1 << INTEL_HDMIF_CLONE_BIT);
 543                 intel_hdmi->ddc_bus = GMBUS_PORT_DPD;
 544                 dev_priv->hotplug_supported_mask |= HDMID_HOTPLUG_INT_STATUS;
 545         }
 546
 547         intel_hdmi->sdvox_reg = sdvox_reg;
 548
 549         if (!HAS_PCH_SPLIT(dev)) {
 550                 intel_hdmi->write_infoframe = i9xx_write_infoframe;
 551                 I915_WRITE(VIDEO_DIP_CTL, 0);
 552         } else {
 553                 intel_hdmi->write_infoframe = ironlake_write_infoframe;
 554                 for_each_pipe(i)
 555                         I915_WRITE(TVIDEO_DIP_CTL(i), 0);
 556         }
 557
 558         drm_encoder_helper_add(&intel_encoder->base, &intel_hdmi_helper_funcs);
 559
 560         intel_hdmi_add_properties(intel_hdmi, connector);
 561
 562         intel_connector_attach_encoder(intel_connector, intel_encoder);
 563         drm_sysfs_connector_add(connector);
 564
 565         /* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
 566          * 0xd.  Failure to do so will result in spurious interrupts being
 567          * generated on the port when a cable is not attached.
 568          */
 569         if (IS_G4X(dev) && !IS_GM45(dev)) {
 570                 u32 temp = I915_READ(PEG_BAND_GAP_DATA);
 571                 I915_WRITE(PEG_BAND_GAP_DATA, (temp & ~0xf) | 0xd);
 572         }
 573 }