[Intel-gfx] [PATCH] drm/i915/skl: Increase ddb blocks to support large cursor sizes

[Ville Syrjälä]

On Fri, Dec 18, 2015 at 06:58:58AM -0800, Matt Roper wrote:
> On Fri, Dec 18, 2015 at 12:35:47PM +0200, Ville Syrjälä wrote:
> > On Wed, Dec 16, 2015 at 07:06:20PM -0800, Radhakrishna Sripada wrote:
> > > Original value of 32 blocks is not sufficient when using cursor size of
> > > 256x256 causing FIFO underruns when the reworked wm
> > > caluclations in
> > > 
> > > commit 024c9045221fe45482863c47c4b4c47d37f97cbf
> > > Author: Matt Roper <matthew.d.roper at intel.com>
> > > Date:   Thu Sep 24 15:53:11 2015 -0700
> > > 
> > >     drm/i915/skl: Eliminate usage of pipe_wm_parameters from SKL-style WM (v4)
> > 
> > Well that commit is obviously incorrect. It's now using the pipe src
> > width as the plane width for all planes.
> > 
> 
> Yeah, we already noted that bug in another email thread, but decided
> that it was unrelated to the problems Radhakrishna is facing.
> Radhakrishna is only using a cursor (which doesn't use that buggy
> function)

Pop quiz: what does it use then?

> and a full-screen primary plane, so the numbers don't actually
> change (for his use case).
> 
> Of course that bug is still worth fixing too; I was planning on writing
> up a patch for it later today.
> 
> 
> Matt
> 
> 
> > > 
> > > are used. Increasing the number of blocks to 52 to make cursor plane tolerate
> > > SAGV block time for the maximum possible cursor size.
> > > 
> > > Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> > > Signed-off-by: Kalyan Kondapally <kalyan.kondapally at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_pm.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > > index d385d99..137fb68 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -2802,7 +2802,7 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
> > >  static unsigned int skl_cursor_allocation(const struct intel_wm_config *config)
> > >  {
> > >  	if (config->num_pipes_active == 1)
> > > -		return 32;
> > > +		return 52;
> > >  
> > >  	return 8;
> > >  }
> > > -- 
> > > 1.9.1
> > > 
> > > _______________________________________________
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> > > Intel-gfx at lists.freedesktop.org
> > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > 
> > -- 
> > Ville Syrjälä
> > Intel OTC
> 
> -- 
> Matt Roper
> Graphics Software Engineer
> IoTG Platform Enabling & Development
> Intel Corporation
> (916) 356-2795

-- 
Ville Syrjälä
Intel OTC