[PATCH v10 5/6] drm/i915/display: handle systems with duplicate psf gv points

[Lisovskiy, Stanislav]

On Fri, Apr 05, 2024 at 02:35:32PM +0300, Vinod Govindapillai wrote:
> From: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> 
> There could be multiple qgv and psf gv points with similar values.
> Apparently pcode's handling og psf and qgv points are different. For
> qgv case, pcode sets whatever is asked by the driver. But in case
> of psf gv points, it compares the bw from points before setting the
> mask. This can cause problems in scenarios where we have to disable
> sagv by setting the highest bw point and there could be multiple
> points with highest bw. So to set the maximum psf gv point, find
> out all the points with the highest bw and set all together.
> 
> v1: - use the same treatment to qgv points as well (Vinod)
> 
> v2: - pcode confirms that for qgv points, it sets whatever the
>       driver sets (Vinod)
> 
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
> Signed-off-by: Vinod Govindapillai <vinod.govindapillai at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_bw.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
> index 5f4f93524bef..6fb228a1a28f 100644
> --- a/drivers/gpu/drm/i915/display/intel_bw.c
> +++ b/drivers/gpu/drm/i915/display/intel_bw.c
> @@ -874,6 +874,8 @@ static unsigned int icl_max_bw_psf_gv_point_mask(struct drm_i915_private *i915)
>  		if (max_data_rate > max_bw) {
>  			max_bw_point_mask = BIT(i);
>  			max_bw = max_data_rate;
> +		} else if (max_data_rate == max_bw) {
> +			max_bw_point_mask |= BIT(i);

So we just came back to where we started. Wondering still, why it even bothers to expose
two equal PSF GV points. Not only having duplicate points doesn't make much sense for 
the driver(since the BW they provide is the same), but also requires some additional
logic on top to handle those.

Stan

>  		}
>  	}
>  
> -- 
> 2.34.1
>