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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sat, 19 Dec 2015, Radhakrishna Sripada <radhakrishna.sripada@intel.com> 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.
>

Sorry the documentation isn't there yet (working on it), but please
always addd

Cc: drm-intel-fixes@lists.freedesktop.org

in the commit message when you're sending a patch there.

BR,
Jani.

> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
> Signed-off-by: Kalyan Kondapally <kalyan.kondapally@intel.com>
> ---
>  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)

-- 
Jani Nikula, Intel Open Source Technology Center
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