Re: [Intel-gfx] [PATCH] drm/i915: Replicate BIOS eDP bpp clamping hack for hsw

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

On Mon, Nov 18, 2013 at 07:38:16AM +0100, Daniel Vetter wrote:
> Haswell's DDI encoders have their own ->get_config callback and in
> 
> commit c6cd2ee2d59111a07cd9199564c9bdcb2d11e5cf
> Author: Jani Nikula <jani.nikula@intel.com>
> Date:   Mon Oct 21 10:52:07 2013 +0300
> 
>     drm/i915/dp: workaround BIOS eDP bpp clamping issue
> 
> we've forgotten to replicate this hack. So let's do it that.
> 
> Note for backporters: The above commit and all it's depencies need to
> be backported first.
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=71049
> Cc: stable@vger.kernel.org
> Tested-by: Gökçen Eraslan <gokcen.eraslan@gmail.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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

Although I might suggest moving the hack into a small function of its
own and calling it from both ddi and dp code.

> ---
>  drivers/gpu/drm/i915/intel_ddi.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index 1591576a6101..330077bcd0bd 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -1406,6 +1406,26 @@ void intel_ddi_get_config(struct intel_encoder *encoder,
>  	default:
>  		break;
>  	}
> +
> +	if (encoder->type == INTEL_OUTPUT_EDP && dev_priv->vbt.edp_bpp &&
> +	    pipe_config->pipe_bpp > dev_priv->vbt.edp_bpp) {
> +		/*
> +		 * This is a big fat ugly hack.
> +		 *
> +		 * Some machines in UEFI boot mode provide us a VBT that has 18
> +		 * bpp and 1.62 GHz link bandwidth for eDP, which for reasons
> +		 * unknown we fail to light up. Yet the same BIOS boots up with
> +		 * 24 bpp and 2.7 GHz link. Use the same bpp as the BIOS uses as
> +		 * max, not what it tells us to use.
> +		 *
> +		 * Note: This will still be broken if the eDP panel is not lit
> +		 * up by the BIOS, and thus we can't get the mode at module
> +		 * load.
> +		 */
> +		DRM_DEBUG_KMS("pipe has %d bpp for eDP panel, overriding BIOS-provided max %d bpp\n",
> +			      pipe_config->pipe_bpp, dev_priv->vbt.edp_bpp);
> +		dev_priv->vbt.edp_bpp = pipe_config->pipe_bpp;
> +	}
>  }
>  
>  static void intel_ddi_destroy(struct drm_encoder *encoder)
> -- 
> 1.8.4.3
> 
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-- 
Ville Syrjälä
Intel OTC