[Intel-gfx] [PATCH 11/14] drm/i915: Fix latency==0 handling for level 0 watermark on skl+

[Matt Roper]

On Thu, Nov 01, 2018 at 05:06:02PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> If the level 0 latency is 0 we can't do anything. Return an error
> rather than success.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Is it possible to get 0 latency here?  I thought we increased the
latency to 2us if punit told us that level0=0 (WaWmMemoryReadLatency)?


Matt

> ---
>  drivers/gpu/drm/i915/intel_pm.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 6fa1634e2db5..bd5f16bc7e08 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -4703,8 +4703,10 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
>  	bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
>  	uint32_t min_disp_buf_needed;
>  
> -	if (latency == 0 ||
> -	    !intel_wm_plane_visible(cstate, intel_pstate)) {
> +	if (latency == 0)
> +		return level == 0 ? -EINVAL : 0;
> +
> +	if (!intel_wm_plane_visible(cstate, intel_pstate)) {
>  		result->plane_en = false;
>  		return 0;
>  	}
> -- 
> 2.18.1
> 
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-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795