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

[Ville Syrjälä]

On Fri, Dec 18, 2015 at 07:14:17AM -0800, Matt Roper wrote:
> On Fri, Dec 18, 2015 at 05:10:12PM +0200, Ville Syrjälä wrote:
> > 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?
> 
> All non-cursor planes (i.e., primary+sprite).  Cursors use a fixed DDB
> allocation (currently 32 blocks as suggested by bspec, but
> Radhakrishna's testing has found this to be too small, so his patch here
> is bumping that number up.

Oh I'm talking about the WM calculation, not the DDB allocation.

-- 
Ville Syrjälä
Intel OTC