drm/i915: Keep the CRC values into a circular buffer

[deliverable/linux.git] / drivers / gpu / drm / i915 / i915_debugfs.c

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 0d8a9a397a245edd1c38731550dbfe42a32cc4ea..991abff94e1e6116b2d162e5af0138de0b67f3ea 100644 (file)
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -27,6 +27,7 @@
  */
 
 #include <linux/seq_file.h>
+#include <linux/circ_buf.h>
 #include <linux/ctype.h>
 #include <linux/debugfs.h>
 #include <linux/slab.h>
@@ -1739,25 +1740,28 @@ static int i915_pipe_crc(struct seq_file *m, void *data)
        struct drm_device *dev = node->minor->dev;
        struct drm_i915_private *dev_priv = dev->dev_private;
        enum pipe pipe = (enum pipe)node->info_ent->data;
-       const struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[pipe];
-       int i;
-       int start;
+       struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[pipe];
+       int head, tail;
 
        if (dev_priv->pipe_crc[pipe].source == INTEL_PIPE_CRC_SOURCE_NONE) {
                seq_puts(m, "none\n");
                return 0;
        }
 
-       start = atomic_read(&pipe_crc->slot) + 1;
        seq_puts(m, " timestamp     CRC1     CRC2     CRC3     CRC4     CRC5\n");
-       for (i = 0; i < INTEL_PIPE_CRC_ENTRIES_NR; i++) {
-               const struct intel_pipe_crc_entry *entry =
-                       &pipe_crc->entries[(start + i) %
-                                          INTEL_PIPE_CRC_ENTRIES_NR];
+       head = atomic_read(&pipe_crc->head);
+       tail = atomic_read(&pipe_crc->tail);
+
+       while (CIRC_CNT(head, tail, INTEL_PIPE_CRC_ENTRIES_NR) >= 1) {
+               struct intel_pipe_crc_entry *entry = &pipe_crc->entries[tail];
 
                seq_printf(m, "%12u %8x %8x %8x %8x %8x\n", entry->timestamp,
                           entry->crc[0], entry->crc[1], entry->crc[2],
                           entry->crc[3], entry->crc[4]);
+
+               BUILD_BUG_ON_NOT_POWER_OF_2(INTEL_PIPE_CRC_ENTRIES_NR);
+               tail = (tail + 1) & (INTEL_PIPE_CRC_ENTRIES_NR - 1);
+               atomic_set(&pipe_crc->tail, tail);
        }
 
        return 0;