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

[Kumar, Shobhit]

On 12/19/2015 05:28 AM, 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)
>
> 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.

This does fix the blanking/unblanking in case of external 4k at 60 DP 
monitor. Will do some test on the patch suggested by Matt in the other mail.

Regards
Shobhit

>
> 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 | 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)
>