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

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Nov 19, 2013 at 05:51:54PM +0200, Ville Syrjälä wrote:
> 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>

Thanks for the review, merged to -fixes.
> 
> Although I might suggest moving the hack into a small function of its
> own and calling it from both ddi and dp code.

I've considered this, but then 90% of the code is the comment explaining
what's going on, so I've figured it's better to duplicate this. If we grow
more edp vbt hacks in ->get_config we can reconsider. But I hope not,
since atm we have no chance to light up the panel if the bios didn't do so
already :(
-Daniel

> 
> > ---
> >  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
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch