[Intel-gfx] [PATCH 08/15] drm/i915: Reject >9 ddi translation entried if port != A/E on SKL

[Ville Syrjälä]

On Thu, Dec 10, 2015 at 02:30:34PM +0100, Daniel Vetter wrote:
> On Tue, Dec 08, 2015 at 07:59:43PM +0200, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Only DDI A and E support 10 translation entries in DP mode. For the
> > other ports the tenth entry is reserved for HDMI..
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_ddi.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index 838cbbe33517..152c813cc43e 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -443,6 +443,10 @@ static void intel_prepare_ddi_buffers(struct drm_i915_private *dev_priv,
> >  		if (dev_priv->vbt.ddi_port_info[port].hdmi_boost_level ||
> >  		    dev_priv->vbt.ddi_port_info[port].dp_boost_level)
> >  			iboost_bit = 1<<31;
> > +
> > +		if (WARN_ON(port != PORT_A &&
> > +			    port != PORT_E && n_edp_entries > 9))
> > +			n_edp_entries = 9;
> 
> Imo WARN_ON just here is enough, set_iboost can only be hit if we pass
> here. With that bikeshed Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

We would then access some unknown registers and memory.

> 
> >  	} else if (IS_BROADWELL(dev_priv)) {
> >  		BUILD_BUG_ON(ARRAY_SIZE(bdw_ddi_translations_fdi) != 9);
> >  		BUILD_BUG_ON(ARRAY_SIZE(bdw_ddi_translations_dp) != 9);
> > @@ -2099,6 +2103,11 @@ static void skl_ddi_set_iboost(struct drm_i915_private *dev_priv,
> >  			iboost = dp_iboost;
> >  		} else {
> >  			ddi_translations = skl_get_buf_trans_edp(dev_priv, &n_entries);
> > +
> > +			if (WARN_ON(port != PORT_A &&
> > +				    port != PORT_E && n_entries > 9))
> > +				n_entries = 9;
> > +
> >  			iboost = ddi_translations[level].i_boost;
> >  		}
> >  	} else if (type == INTEL_OUTPUT_HDMI) {
> > -- 
> > 2.4.10
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC