Re: [PATCH v13 17/17] drm/i915: Display WA 827

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

Op 09-03-18 om 09:49 schreef Vidya Srinivas:
> Display WA 827 applies to GEN9 (excluede GLK) and CNL.
> Switching the plane format from NV12 to RGB and leaving system idle
> results in display underrun and corruption.
> WA: Set the bit 15 & bit 19 to 1b in the CLKGATE_DIS_PSL
> register for the pipe in which NV12 plane is enabled.
>
> Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
> Signed-off-by: Nabendu Maiti <nabendu.bikash.maiti@intel.com>
> Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h      |  3 +++
>  drivers/gpu/drm/i915/intel_display.c | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 8e61b68..dd8ee98 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3939,6 +3939,9 @@ enum {
>  #define _CLKGATE_DIS_PSL_A		0x46520
>  #define _CLKGATE_DIS_PSL_B		0x46524
>  #define _CLKGATE_DIS_PSL_C		0x46528
> +#define   DUPS1_GATING_DIS		(1 << 15)
> +#define   DUPS2_GATING_DIS		(1 << 19)
> +#define   DUPS3_GATING_DIS		(1 << 23)
>  #define   DPF_GATING_DIS		(1 << 10)
>  #define   DPF_RAM_GATING_DIS		(1 << 9)
>  #define   DPFR_GATING_DIS		(1 << 8)
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 941f00d..f5fdf8a 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -504,6 +504,21 @@ static const struct intel_limit intel_limits_bxt = {
>  	.p2 = { .p2_slow = 1, .p2_fast = 20 },
>  };
>  
> +static void
> +skl_wa_clkgate(struct drm_i915_private *dev_priv, int pipe, bool enable)
> +{
> +	if (IS_SKYLAKE(dev_priv))
> +		return;
> +
> +	if (enable)
> +		I915_WRITE(CLKGATE_DIS_PSL(pipe),
> +			   DUPS1_GATING_DIS | DUPS2_GATING_DIS);
> +	else
> +		I915_WRITE(CLKGATE_DIS_PSL(pipe),
> +			   I915_READ(CLKGATE_DIS_PSL(pipe)) &
> +			   ~(DUPS1_GATING_DIS|DUPS2_GATING_DIS));
> +}
> +
>  static bool
>  needs_modeset(const struct drm_crtc_state *state)
>  {
> @@ -3151,6 +3166,9 @@ int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
>  	const struct drm_framebuffer *fb = plane_state->base.fb;
>  	unsigned int rotation = plane_state->base.rotation;
>  	int ret;
> +	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
> +	struct drm_i915_private *dev_priv =
> +		to_i915(plane_state->base.plane->dev);
>  
>  	if (rotation & DRM_MODE_REFLECT_X &&
>  	    fb->modifier == DRM_FORMAT_MOD_LINEAR) {
> @@ -3175,6 +3193,13 @@ int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
>  		ret = skl_check_nv12_aux_surface(plane_state);
>  		if (ret)
>  			return ret;
> +
> +		/* Display WA 827 */
> +		if (INTEL_GEN(dev_priv) == 9 || IS_CANNONLAKE(dev_priv)) {
> +			if (!IS_GEMINILAKE(dev_priv))
> +				skl_wa_clkgate(dev_priv,
> +					       intel_crtc->pipe, true);
> +		}
>  	} else if (fb->modifier == I915_FORMAT_MOD_Y_TILED_CCS ||
>  		   fb->modifier == I915_FORMAT_MOD_Yf_TILED_CCS) {
>  		ret = skl_check_ccs_aux_surface(plane_state);
This is absolutely the wrong place to put this. atomic check can be called without any power well
enabled, and the only way  The right place is intel_pre_plane_update/intel_post_plane_update.

We already have a active_planes property, so we would need something similar for nv12 planes.

In pre_plane_update, we could enable the w/a if new_crtc_state->nv12_planes.
In post_plane_update, we can disable it if !new_crtc_state->nv12_planes.

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