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drm/i915: Make vblank evade warnings optional

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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 <daniel@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reported-by: Jens Axboe <axboe@kernel.dk>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: e1edbd44e2 ("drm/i915: Complain if we take too long under vblank evasion.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Ville Syrjälä 2017-05-07 20:12:52 +03:00 committed by Dave Airlie
parent bb57d0411a
commit 7b8cd3363e
2 changed files with 18 additions and 2 deletions
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13
drivers/gpu/drm/i915/Kconfig.debug
View File

@ -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".

7
drivers/gpu/drm/i915/intel_sprite.c
View File

@ -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