[Intel-gfx] [PATCH] drm/i915/cnp: Properly handle VBT ddc pin out of bounds.

[Rodrigo Vivi]

On Mon, Jan 29, 2018 at 05:42:53AM +0000, Kai Heng Feng wrote:
> 
> > On 26 Jan 2018, at 6:25 AM, Rodrigo Vivi <rodrigo.vivi at intel.com> wrote:
> > 
> > If the table result is out of bounds on the array map
> > there is something really wrong with VBT pin so we don't
> > return that vbt_pin, but only return 0 instead.
> > 
> > This basically reverts commit 'a8e6f3888b05 ("drm/i915/cnp:
> > Ignore VBT request for know invalid DDC pin.")'
> > 
> > Also this properly fixes commit 9c3b2689d01f ("drm/i915/cnl:
> > Map VBT DDC Pin to BSpec DDC Pin.")
> > 
> > v2: Do in a way that we don't break other platforms. (Jani)
> > 
> > v3: Keep debug message (Jani)
> > 
> > v4: Don't mess with 0 mapping was noticed by Jani and
> >    addressed with a simple solution suggested by Lucas
> >    that makes this even simpler.
> > 
> > Fixes: a8e6f3888b05 ("drm/i915/cnp: Ignore VBT request for know invalid DDC pin.")
> > Fixes: 9c3b2689d01f ("drm/i915/cnl: Map VBT DDC Pin to BSpec DDC Pin.")
> > Cc: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> > Cc: Jani Nikula <jani.nikula at intel.com>
> > Cc: Kai Heng Feng <kai.heng.feng at canonical.com>
> > Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> > Suggested-by: Lucas De Marchi <lucas.demarchi at intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> 
> Tested-by: Kai-Heng Feng <kai.heng.feng at canonical.com>

merged. thanks for suggestions, reviews, tests and patience ;)

> 
> > ---
> > drivers/gpu/drm/i915/intel_bios.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> > index 95f0b310d656..cf3f8f1ba6f7 100644
> > --- a/drivers/gpu/drm/i915/intel_bios.c
> > +++ b/drivers/gpu/drm/i915/intel_bios.c
> > @@ -1107,6 +1107,7 @@ static void sanitize_aux_ch(struct drm_i915_private *dev_priv,
> > }
> > 
> > static const u8 cnp_ddc_pin_map[] = {
> > +	[0] = 0, /* N/A */
> > 	[DDC_BUS_DDI_B] = GMBUS_PIN_1_BXT,
> > 	[DDC_BUS_DDI_C] = GMBUS_PIN_2_BXT,
> > 	[DDC_BUS_DDI_D] = GMBUS_PIN_4_CNP, /* sic */
> > @@ -1116,9 +1117,9 @@ static const u8 cnp_ddc_pin_map[] = {
> > static u8 map_ddc_pin(struct drm_i915_private *dev_priv, u8 vbt_pin)
> > {
> > 	if (HAS_PCH_CNP(dev_priv)) {
> > -		if (vbt_pin > 0 && vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map))
> > +		if (vbt_pin < ARRAY_SIZE(cnp_ddc_pin_map)) {
> > 			return cnp_ddc_pin_map[vbt_pin];
> > -		if (vbt_pin > GMBUS_PIN_4_CNP) {
> > +		} else {
> > 			DRM_DEBUG_KMS("Ignoring alternate pin: VBT claims DDC pin %d, which is not valid for this platform\n", vbt_pin);
> > 			return 0;
> > 		}
> > -- 
> > 2.13.6
> > 
>