Re: [PATCH 2/2] drm/omapdrm: Move commit_modeset_enables() before commit_planes()

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jyri,

On Monday 30 Jan 2017 13:11:56 Jyri Sarha wrote:
> On 01/28/17 18:17, Laurent Pinchart wrote:
> > On Friday 27 Jan 2017 12:04:55 Jyri Sarha wrote:
> >> Move drm_atomic_helper_commit_modeset_enables() call to before
> >> drm_atomic_helper_commit_planes() call and have a
> >> omap_atomic_wait_for_completion() call after both.
> >> 
> >> With the current dss dispc implementation we have to enable the new
> >> modeset before we can commit planes. The dispc ovl configuration
> >> relies on the video mode configuration been written into the HW when
> >> the ovl configuration is calculated.
> >> 
> >> This approach is not ideal because after a mode change the plane
> >> update is executed only after the first vblank interrupt. The dispc
> >> implementation should be fixed so that it is able use uncommitted drm
> >> state information.  information.
> >> 
> >> Signed-off-by: Jyri Sarha <jsarha@ti.com>
> >> ---
> >> 
> >>  drivers/gpu/drm/omapdrm/omap_drv.c | 16 +++++++++++++++-
> >>  1 file changed, 15 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c
> >> b/drivers/gpu/drm/omapdrm/omap_drv.c index 5e55f1b..8c15735 100644
> >> --- a/drivers/gpu/drm/omapdrm/omap_drv.c
> >> +++ b/drivers/gpu/drm/omapdrm/omap_drv.c
> >> @@ -96,8 +96,22 @@ static void omap_atomic_complete(struct
> >> omap_atomic_state_commit *commit) dispc_runtime_get();
> >> 
> >>  	drm_atomic_helper_commit_modeset_disables(dev, old_state);
> >> 
> >> -	drm_atomic_helper_commit_planes(dev, old_state, 0);
> >> +
> >> +	/* With the current dss dispc implementation we have to enable
> >> +	 * the new modeset before we can commit planes. The dispc ovl
> >> +	 * configuration relies on the video mode configuration been
> >> +	 * written into the HW when the ovl configuration is
> >> +	 * calculated.
> >> +	 *
> >> +	 * This approach is not ideal because after a mode change the
> >> +	 * plane update is executed only after the first vblank
> >> +	 * interrupt. The dispc implementation should be fixed so that
> >> +	 * it is able use uncommitted drm state information.
> > 
> > Any chance you could fix the dispc implementation ? ;-) Otherwise, could
> > you
>
> I am currently studying how to do it, but it tricky... really tricky. In
> DRM terms, the plane configuration is affected by the connector where
> the crtc is connected to. The whole DSS should have to made understand
> drm state structures. There certainly wont be any "fix" for 4.10,
> probably nothing for 4.11 either.
> 
> > rebase (and retest) this patch on top of "[PATCH 0/5] omapdrm: fences and
> > zpos" ?
> 
> Thanks, I'll do that.

If you intend on merging this patch as a v4.10 fix then there's no need to 
rebase. If it targets v4.11, the above-mentioned series will likely go in 
first.

-- 
Regards,

Laurent Pinchart

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