[Intel-gfx] [PATCH] drm/i915/cnl: Wa to ignore VBT alternate pin on B-stepping.

[Vivi, Rodrigo]

On Fri, 2017-04-07 at 16:19 +0300, Ville Syrjälä wrote:
> On Thu, Apr 06, 2017 at 05:54:26PM -0700, Rodrigo Vivi wrote:
> > Current VBT available for pre-production machines
> > tells that we need to use alternate pin. But if we use it
> > we end up needing to define a different table.
> > 
> > However if we respect the spec, ignore the VBT for now
> > we get a more reliable HDMI.
> > 
> > Cc: Clint Taylor <clinton.a.taylor at intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_hdmi.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> > index f8c40ae..0d389bc 100644
> > --- a/drivers/gpu/drm/i915/intel_hdmi.c
> > +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> > @@ -1884,7 +1884,8 @@ static u8 intel_hdmi_ddc_pin(struct drm_i915_private *dev_priv,
> >  		&dev_priv->vbt.ddi_port_info[port];
> >  	u8 ddc_pin;
> >  
> > -	if (info->alternate_ddc_pin) {
> > +	if (info->alternate_ddc_pin &&
> > +	    !IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0)) {
> 
> So it's got broken VBT? In that case it would make more sense to me
> to put the kludge into the VBT parsing code.

yeap. It makes sense. I will move that to there later.
Thanks.

> 
> >  		DRM_DEBUG_KMS("Using DDC pin 0x%x for port %c (VBT)\n",
> >  			      info->alternate_ddc_pin, port_name(port));
> >  		return info->alternate_ddc_pin;
> > -- 
> > 1.9.1
> > 
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>