drm/i915: Make vblank evade warnings optional

7b8cd336 · Ville Syrjälä <[email protected]> · 2017-05-07 20:12:52 +03:00

Add a new Kconfig option to enable/disable the extra warnings
from the vblank evade code. For now we'll keep the warning
about an actually missed vblank always enabled as that can have
an actual user visible impact. But if we miss the deadline
othrwise there's no real need to bother the user with that.
We'll want these warnings enabled during development however
so that we can catch regressions.

Based on the reports it looks like this is still very easy
to hit on SKL, so we have more work ahead of us to optimize
the crtiical section further.

Cc: Daniel Vetter <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Maarten Lankhorst <[email protected]>
Reported-by: Jens Axboe <[email protected]>
Reported-by: Linus Torvalds <[email protected]>
Fixes: e1edbd44e23b ("drm/i915: Complain if we take too long under vblank evasion.")
Signed-off-by: Ville Syrjälä <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
Signed-off-by: Dave Airlie <[email protected]>

Commit: 7b8cd3363e8a0e6b90a7067f75aaeaae61a7d612
Parents: bb57d041

Changes

2 files changed · +18 −2

File	Status	Add	Del	Content
drivers/gpu/drm/i915/Kconfig.debug	modified	+13	−0	View file
drivers/gpu/drm/i915/intel_sprite.c	modified	+5	−2	View file

drivers/gpu/drm/i915/Kconfig.debug

View file

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index e091809..b00edd3 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -87,3 +87,16 @@ config DRM_I915_LOW_LEVEL_TRACEPOINTS
           and also analyze the request dependency resolving timeline.
 
           If in doubt, say "N".
+
+config DRM_I915_DEBUG_VBLANK_EVADE
+	bool "Enable extra debug warnings for vblank evasion"
+	depends on DRM_I915
+	default n
+	help
+	  Choose this option to turn on extra debug warnings for the
+	  vblank evade mechanism. This gives a warning every time the
+	  the deadline allotted for the vblank evade critical section
+	  is exceeded, even if there isn't an actual risk of missing
+	  the vblank.
+
+	  If in doubt, say "N".

drivers/gpu/drm/i915/intel_sprite.c

View file

diff --git a/drivers/gpu/drm/i915/intel_sprite.c b/drivers/gpu/drm/i915/intel_sprite.c
index f7d4314..8c87c71 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -198,12 +198,15 @@ void intel_pipe_update_end(struct intel_crtc *crtc, struct intel_flip_work *work
 			  ktime_us_delta(end_vbl_time, crtc->debug.start_vbl_time),
 			  crtc->debug.min_vbl, crtc->debug.max_vbl,
 			  crtc->debug.scanline_start, scanline_end);
-	} else if (ktime_us_delta(end_vbl_time, crtc->debug.start_vbl_time) >
-		   VBLANK_EVASION_TIME_US)
+	}
+#ifdef CONFIG_DRM_I915_DEBUG_VBLANK_EVADE
+	else if (ktime_us_delta(end_vbl_time, crtc->debug.start_vbl_time) >
+		 VBLANK_EVASION_TIME_US)
 		DRM_WARN("Atomic update on pipe (%c) took %lld us, max time under evasion is %u us\n",
 			 pipe_name(pipe),
 			 ktime_us_delta(end_vbl_time, crtc->debug.start_vbl_time),
 			 VBLANK_EVASION_TIME_US);
+#endif
 }
 
 static void