Re: [PATCH] drm/i915: Fix frontbuffer false positve.

From: Matt Roper <matthew.d.roper@intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org, Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH] drm/i915: Fix frontbuffer false positve.
Date: Tue, 24 Feb 2015 13:01:29 -0800	[thread overview]
Message-ID: <20150224210129.GR594@intel.com> (raw)
In-Reply-To: <20150224203825.GD24485@phenom.ffwll.local>

On Tue, Feb 24, 2015 at 09:38:25PM +0100, Daniel Vetter wrote:
> On Tue, Feb 24, 2015 at 10:44:19AM -0800, Matt Roper wrote:
> > On Tue, Feb 24, 2015 at 10:36:32AM -0800, Rodrigo Vivi wrote:
> > > Atomic bits needs to be set when cursor check function is returning 0
> > > and intel_crtc is active.
> > > 
> > > v2: When putting more debug prints I notice the solution was simpler
> > > than I thought. AMS design is solid, just this return was wrong.
> > > Sorry for the noise.
> > > 
> > > Cc: Matt Roper <matthew.d.roper@intel.com>
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > 
> > Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
> > 
> > > ---
> > >  drivers/gpu/drm/i915/intel_display.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index 8ccf033..5fb83ba 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -12198,7 +12198,7 @@ intel_check_cursor_plane(struct drm_plane *plane,
> > >  	}
> > >  
> > >  	if (fb == crtc->cursor->fb)
> > > -		return 0;
> > > +		goto finish;
> 
> Shouldn't we just delete this check entirely? gcc will do it anyway for
> us. When you do that you can also append the history I've dug out for
> this.

Yeah, that seems reasonable too.  The only thing we're actually skipping
at the moment is a tiling check which should never come true in this
case (otherwise we would have already failed on a previous cursor
update).

Matt

> 
> The original regression seems to have been introduced in the original
> check/commit split:
> 
> commit 757f9a3e5b8a812af0c213099a5b31cb423f4d3c
> Author: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> Date:   Wed Sep 24 14:20:24 2014 -0300
> 
>     drm/i915: move check of intel_crtc_cursor_set_obj() out
> 
> Which already cause other trouble, resulting in the check getting moved in
> 
> commit e391ea882b1a04fb3f559287ac694652a3cd9da9
> Author: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> Date:   Wed Sep 24 14:20:25 2014 -0300
> 
>     drm/i915: Fix not checking cursor and object sizes
> 
> The frontbuffer tracking itself only was broken when we shifted it into
> the check/commit logic with:
> 
> commit 32b7eeec4d1e861230b09d437e95d76c86ff4a68
> Author: Matt Roper <matthew.d.roper@intel.com>
> Date:   Wed Dec 24 07:59:06 2014 -0800
> 
>     drm/i915: Refactor work that can sleep out of commit (v7)
> 
> Cheers, Daniel
> > >  
> > >  	if (fb->modifier[0] != DRM_FORMAT_MOD_NONE) {
> > >  		DRM_DEBUG_KMS("cursor cannot be tiled\n");
> > > -- 
> > > 2.1.0
> > > 
> > 
> > -- 
> > Matt Roper
> > Graphics Software Engineer
> > IoTG Platform Enabling & Development
> > Intel Corporation
> > (916) 356-2795
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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