Re: [PATCH v2 1/3] drm/i915: Force background color to black for gen9+

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Matt Roper <matthew.d.roper@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH v2 1/3] drm/i915: Force background color to black for gen9+
Date: Wed, 14 Nov 2018 19:28:12 +0200	[thread overview]
Message-ID: <20181114172812.GS9144@intel.com> (raw)
In-Reply-To: <20181113232149.22753-2-matthew.d.roper@intel.com>

On Tue, Nov 13, 2018 at 03:21:47PM -0800, Matt Roper wrote:
> We don't yet allow userspace to control the CRTC background color, but
> we should manually program the color to black to ensure the BIOS didn't
> leave us with some other color.  We should also set the pipe gamma and
> pipe CSC bits so that the background color goes through the same color
> management transformations that a plane with black pixels would.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
> We may want to land this patch before the rest of the series since it's
> still valuable even without the new ABI the rest of the series adds.
> 
>  drivers/gpu/drm/i915/i915_reg.h      |  6 ++++++
>  drivers/gpu/drm/i915/intel_display.c | 18 ++++++++++++++++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index fe4b913e46ac..b92a721c9bcb 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5662,6 +5662,12 @@ enum {
>  #define   PIPEMISC_DITHER_TYPE_SP	(0 << 2)
>  #define PIPEMISC(pipe)			_MMIO_PIPE2(pipe, _PIPE_MISC_A)
>  
> +/* Skylake+ pipe bottom (background) color */
> +#define _SKL_CANVAS_A			0x70034
> +#define   SKL_CANVAS_GAMMA_ENABLE	(1 << 31)
> +#define   SKL_CANVAS_CSC_ENABLE		(1 << 30)
> +#define SKL_CANVAS(pipe)		_MMIO_PIPE2(pipe, _SKL_CANVAS_A)

Didn't the spec call this BOTTOM_COLOR or something like that?

> +
>  #define VLV_DPFLIPSTAT				_MMIO(VLV_DISPLAY_BASE + 0x70028)
>  #define   PIPEB_LINE_COMPARE_INT_EN		(1 << 29)
>  #define   PIPEB_HLINE_INT_EN			(1 << 28)
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 132e978227fb..1d089d93d88b 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -3868,6 +3868,15 @@ static void intel_update_pipe_config(const struct intel_crtc_state *old_crtc_sta
>  		else if (old_crtc_state->pch_pfit.enabled)
>  			ironlake_pfit_disable(old_crtc_state);
>  	}
> +
> +	/*
> +	 * We don't (yet) allow userspace to control the pipe background color,
> +	 * so force it to black, but apply pipe gamma and CSC so that its
> +	 * handling will match how we program our planes.
> +	 */
> +	if (INTEL_GEN(dev_priv) >= 9)
> +		I915_WRITE(SKL_CANVAS(crtc->pipe),
> +			   SKL_CANVAS_GAMMA_ENABLE | SKL_CANVAS_CSC_ENABLE);
>  }
>  
>  static void intel_fdi_normal_train(struct intel_crtc *crtc)
> @@ -15356,6 +15365,15 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc,
>  			    plane->base.type != DRM_PLANE_TYPE_PRIMARY)
>  				intel_plane_disable_noatomic(crtc, plane);
>  		}
> +
> +		/*
> +		 * Disable any background color set by the BIOS, but enable the
> +		 * gamma and CSC to match how we program our planes.
> +		 */
> +		if (INTEL_GEN(dev_priv) >= 9)
> +			I915_WRITE(SKL_CANVAS(crtc->pipe),
> +				   SKL_CANVAS_GAMMA_ENABLE |
> +				   SKL_CANVAS_CSC_ENABLE);
>  	}
>  
>  	/* Adjust the state of the output pipe according to whether we
> -- 
> 2.14.4

-- 
Ville Syrjälä
Intel
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