[RFC 3/3] drm/i915: add underrun counts to i915_display_info

Joe Konno
2016-01-26T19:36:58Z

From: Joe Konno <joe.konno@intel.com>

Add atomic cpu and pch underrun counters to struct intel_crtc, and
increment them each time their respective interrupt handler executes.

Whether dmesg underrun reporting is disabled or not, keep a count of cpu
and pch underrun interrupts. Display these counts in i915_display_info
on a per-pipe. per-transcoder basis to assist debugging and testing.

In debugfs, the i915_display_info output for each pipe changes from
this:
underrun reporting: cpu=%s pch=%s

to this, where the number of underruns are reported in parentheses:
underrun reporting: cpu=%s (%d) pch=%s (%d)

Signed-off-by: Joe Konno <joe.konno@intel.com>
---
drivers/gpu/drm/i915/i915_debugfs.c | 6 ++++--
drivers/gpu/drm/i915/intel_drv.h | 4 ++++
drivers/gpu/drm/i915/intel_fifo_underrun.c | 6 ++++++
3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 863012a2602e..aa47987bb13b 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3101,9 +3101,11 @@ static int i915_display_info(struct seq_file *m, void *unused)
intel_plane_info(m, crtc);
}

- seq_printf(m, "\tunderrun reporting: cpu=%s pch=%s \n",
+ seq_printf(m, "\tunderrun reporting: cpu=%s (%d) pch=%s (%d) \n",
yesno(!crtc->cpu_fifo_underrun_disabled),
- yesno(!crtc->pch_fifo_underrun_disabled));
+ atomic_read(&crtc->cpu_fifo_underrun_count),
+ yesno(!crtc->pch_fifo_underrun_disabled),
+ atomic_read(&crtc->pch_fifo_underrun_count));
}

seq_printf(m, "\n");
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index bc970125ec76..efc6eb0a517f 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -589,6 +589,10 @@ struct intel_crtc {
/* reset counter value when the last flip was submitted */
unsigned int reset_counter;

+ /* fifo_underrun counters, used in debugfs only */
+ atomic_t cpu_fifo_underrun_count;
+ atomic_t pch_fifo_underrun_count;
+
/* Access to these should be protected by dev_priv->irq_lock. */
bool cpu_fifo_underrun_disabled;
bool pch_fifo_underrun_disabled;
diff --git a/drivers/gpu/drm/i915/intel_fifo_underrun.c b/drivers/gpu/drm/i915/intel_fifo_underrun.c
index 4a1a2781fc5e..d7b355b831e1 100644
--- a/drivers/gpu/drm/i915/intel_fifo_underrun.c
+++ b/drivers/gpu/drm/i915/intel_fifo_underrun.c
@@ -407,6 +407,9 @@ void intel_cpu_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,

report = intel_get_cpu_fifo_underrun_reporting(dev_priv, pipe);

+ /* Increment the debugfs underrun counter */
+ atomic_inc(&to_intel_crtc(crtc)->cpu_fifo_underrun_count);
+
if (report)
DRM_ERROR_RATELIMITED("CPU pipe %c FIFO underrun\n",
pipe_name(pipe));
@@ -427,6 +430,9 @@ void intel_pch_fifo_underrun_irq_handler(struct drm_i915_private *dev_priv,
bool report = intel_get_pch_fifo_underrun_reporting(dev_priv,
pch_transcoder);

+ /* Increment the debugfs underrun counter */
+ atomic_inc(&to_intel_crtc(crtc)->pch_fifo_underrun_count);
+
if (report)
DRM_ERROR_RATELIMITED("PCH transcoder %c FIFO underrun\n",
transcoder_name(pch_transcoder));
--
2.6.4