Re: [Intel-gfx] [PATCH] drm/i915/dg2: Implement WM0 cursor WA for DG2

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

On Thu, 18 Nov 2021, Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> wrote:
> Bug in the register unit which results in WM1 register
> used when only WM0 is enabled on cursor.
> Software workaround is when only WM0 enabled on cursor,
> copy contents of CUR_WM_0[30:0] (exclude the enable bit)
> into CUR_WM_1[30:0].
>
> v2:  - s/dev_priv/i915/ (Ville Syrjälä)
>      - Removed unneeded brackets (Ville Syrjälä)
>
> HSDES: 14012656716
>
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 89dc7f69baf3..01fa3fac1b57 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5095,6 +5095,18 @@ skl_check_nv12_wm_level(struct skl_wm_level *wm, struct skl_wm_level *uv_wm,
>  	}
>  }
>  
> +static bool icl_need_wm1_wa(struct drm_i915_private *i915,
> +			    enum plane_id plane_id)

Commit subject having "WM0 cursor WA" and the function saying "wm1_wa"
looks like a discrepancy to the casual reader.

BR,
Jani.

> +{
> +	/*
> +	 * Wa_1408961008:icl, ehl
> +	 * Wa_14012656716:tgl, adl
> +	 * Underruns with WM1+ disabled
> +	 */
> +	return DISPLAY_VER(i915) == 11 ||
> +	       (IS_DISPLAY_VER(i915, 12, 13) && plane_id == PLANE_CURSOR);
> +}
> +
>  static int
>  skl_allocate_plane_ddb(struct intel_atomic_state *state,
>  		       struct intel_crtc *crtc)
> @@ -5265,11 +5277,7 @@ skl_allocate_plane_ddb(struct intel_atomic_state *state,
>  			skl_check_nv12_wm_level(&wm->wm[level], &wm->uv_wm[level],
>  						total[plane_id], uv_total[plane_id]);
>  
> -			/*
> -			 * Wa_1408961008:icl, ehl
> -			 * Underruns with WM1+ disabled
> -			 */
> -			if (DISPLAY_VER(dev_priv) == 11 &&
> +			if (icl_need_wm1_wa(dev_priv, plane_id) &&
>  			    level == 1 && wm->wm[0].enable) {
>  				wm->wm[level].blocks = wm->wm[0].blocks;
>  				wm->wm[level].lines = wm->wm[0].lines;

-- 
Jani Nikula, Intel Open Source Graphics Center