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

[Matt Roper]

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) 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
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > 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