Re: [PATCH 02/15] drm/i915: Disable high-bpc on pre-1.4 EDID screens

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Apr 19, 2013 at 11:24:34AM +0200, Daniel Vetter wrote:
> Prevents black screens when using 30bpp framebuffers on my
> HDMI screens here. The DP input on the same screen though reports a
> 1.4 EDID with the correct 8bpc limit set.
> 
> v2: Actually check for the right thing!
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 6e265b0..1e6efab 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -7612,6 +7612,13 @@ pipe_config_set_bpp(struct drm_crtc *crtc,
>  				      bpp, connector->display_info.bpc*3);
>  			pipe_config->pipe_bpp = connector->display_info.bpc*3;
>  		}
> +
> +		/* Clamp bpp to 8 on screens without EDID 1.4 */
> +		if (connector->display_info.bpc == 0 && bpp > 24) {
> +			DRM_DEBUG_KMS("clamping display bpp (was %d) to default limit of 24\n",
> +				      bpp);
> +			pipe_config->pipe_bpp = 24;
> +		}
>  	}
>  
>  	return bpp;
> -- 
> 1.7.11.7
> 
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-- 
Ville Syrjälä
Intel OTC