Re: [PATCH v2] drm/i915/skl: Increase ddb blocks to support large cursor sizes

[Matt Roper <matthew.d.roper@intel.com>]

On Mon, Dec 21, 2015 at 11:15:04AM +0530, Kumar, Shobhit wrote:
> On 12/19/2015 08:14 AM, Matt Roper wrote:
> >On Fri, Dec 18, 2015 at 03:58:52PM -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@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)
> >>
> >>are used. Increasing the number of blocks to 52 to make cursor plane tolerate
> >>SAGV block time for the maximum possible cursor size.
> >>
> >>v2: Included Matt's suggestion, bumping up the no of blocks in multi-pipe case
> >>to 16.
> >>
> >>Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
> >>Signed-off-by: Kalyan Kondapally <kalyan.kondapally@intel.com>
> >
> >Can you try my patch "drm/i915/skl: Use proper plane dimensions for DDB
> >and WM calculations" first and see if it solves your problems?  It's
> 
> Where can I find this patch ? Couldn't find in drm-intel branches or
> the mailing list.

Yeah, looks like I mistyped the mailing list address for git-send-email;
just resent with the proper address...you can find it here:

        http://patchwork.freedesktop.org/patch/68786/


Matt

> 
> Regards
> Shobhit
> 
> >possible that your problems were caused by my fumble that I'm fixing
> >with that patch; if that patch fixes the problem, then we may not need
> >to alter the cursor's fixed allocation after all.
> >
> >Of course as we noted, there are a handful of new workarounds in the
> >bspec (SAGV disabling, system memory bandwidth checking, etc.) that we
> >still don't have in our driver yet, so if any of those are the true root
> >cause, then your patch here is probably a reasonable short-term fix
> >until we can take action on the new workarounds.  In that case, you can
> >consider this patch
> >
> >Acknowledged-by: Matt Roper <matthew.d.roper@intel.com>
> >
> >Unfortunately I only have a BXT which doesn't exhibit the problems
> >you're seeing, so I can't actually test this out myself.
> >
> >
> >Matt
> >
> >>---
> >>  drivers/gpu/drm/i915/intel_pm.c | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> >>index d385d99..c5ba4e5 100644
> >>--- a/drivers/gpu/drm/i915/intel_pm.c
> >>+++ b/drivers/gpu/drm/i915/intel_pm.c
> >>@@ -2802,9 +2802,9 @@ 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;
> >>+	return 16;
> >>  }
> >>
> >>  static void skl_ddb_entry_init_from_hw(struct skl_ddb_entry *entry, u32 reg)
> >>--
> >>1.9.1
> >>
> >

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