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SubjectRe: [Intel-gfx] [PATCH] drm/i915: Fix screen flickering on X
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On Thu, 07 May 2015, Matt Roper <matthew.d.roper@intel.com> wrote:
> On Thu, May 07, 2015 at 12:12:18PM +0300, Jani Nikula wrote:
>> On Thu, 23 Apr 2015, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>> > [cc'ing the authors]
>>
>> This has been posted earlier [1] and it has review to be addressed [2].
>>
>> BR,
>> Jani.
>
> I agree with Ander's response in [2]...we can't call
> intel_update_watermarks() in the commit function because we're under
> vblank evasion. We should already be flagging the transaction as
> needing a watermark update in intel_check_cursor_plane(), and that flag
> will be acted upon immediately after the commit functions are done
> running, once we've re-enabled interrupts.
>
> Note that our current codebase looks a bit different since we've dropped
> intel_crtc->cursor_{width,height}. So the relevant check in
> intel_check_cursor_plane() now looks like:
>
> if (plane->state->crtc_w != state->base.crtc_w)
> intel_crtc->atomic.update_wm = true;
>
> Is there a bugzilla open on this issue with more details?

Not that I know of. Ismael?

BR,
Jani.


>
>
> Matt
>
>>
>>
>> [1] http://mid.gmane.org/1428790644-6812-1-git-send-email-ismael@iodev.co.uk
>> [2] http://mid.gmane.org/1428928418.2654.8.camel@gmail.com
>>
>>
>> >
>> > On Sat, Apr 11, 2015 at 07:40:34PM -0300, Ismael Luceno wrote:
>> >> A bisect showed that commit 32b7eeec4d1e861230b09d437e95d76c86ff4a68
>> >> introduced the issue.
>> >>
>> >> The issue starts as soon as X takes control of the screen, even if just
>> >> a plain X doing nothing, so based on the code touched by the commit I
>> >> thought it had to be related to the so called "hardware cursor". I
>> >> confirmed it when hiding the cursor made the flickering go away.
>> >>
>> >> The aforementioned commit removed some suspicious code, and the
>> >> Programmer's Reference Manual confirmed my suspicion:
>> >>
>> >> "Incorrectly programmed watermark values can result in screen corruption.
>> >>
>> >> The watermarks should be calculated and programmed when any of the
>> >> watermark calculation inputs change. This includes planes enabling or
>> >> disabling, plane source format or size changing, etc."
>> >>
>> >> So I'm re-adding the few lines that update the watermarks after a cursor
>> >> size change.
>> >>
>> >> Signed-off-by: Ismael Luceno <ismael@iodev.co.uk>
>> >> ---
>> >> drivers/gpu/drm/i915/intel_display.c | 7 ++++++-
>> >> 1 file changed, 6 insertions(+), 1 deletion(-)
>> >>
>> >> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> >> index f75173c..e23f062 100644
>> >> --- a/drivers/gpu/drm/i915/intel_display.c
>> >> +++ b/drivers/gpu/drm/i915/intel_display.c
>> >> @@ -12258,6 +12258,7 @@ intel_commit_cursor_plane(struct drm_plane *plane,
>> >> struct intel_crtc *intel_crtc;
>> >> struct intel_plane *intel_plane = to_intel_plane(plane);
>> >> struct drm_i915_gem_object *obj = intel_fb_obj(state->base.fb);
>> >> + unsigned old_width;
>> >> uint32_t addr;
>> >>
>> >> crtc = crtc ? crtc : plane->crtc;
>> >> @@ -12282,11 +12283,15 @@ intel_commit_cursor_plane(struct drm_plane *plane,
>> >> intel_crtc->cursor_addr = addr;
>> >> intel_crtc->cursor_bo = obj;
>> >> update:
>> >> + old_width = intel_crtc->cursor_width;
>> >> intel_crtc->cursor_width = state->base.crtc_w;
>> >> intel_crtc->cursor_height = state->base.crtc_h;
>> >>
>> >> - if (intel_crtc->active)
>> >> + if (intel_crtc->active) {
>> >> + if (old_width != intel_crtc->cursor_width)
>> >> + intel_update_watermarks(crtc);
>> >> intel_crtc_update_cursor(crtc, state->visible);
>> >> + }
>> >> }
>> >>
>> >> static struct drm_plane *intel_cursor_plane_create(struct drm_device *dev,
>> >> --
>> >> 2.3.4
>> >
>> > --
>> > Chris Wilson, Intel Open Source Technology Centre
>> > _______________________________________________
>> > Intel-gfx mailing list
>> > Intel-gfx@lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>> --
>> Jani Nikula, Intel Open Source Technology Center
>
> --
> Matt Roper
> Graphics Software Engineer
> IoTG Platform Enabling & Development
> Intel Corporation
> (916) 356-2795

--
Jani Nikula, Intel Open Source Technology Center


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