[Intel-gfx] [PATCH] drm/i915: 4K audio N value incorrect at 29.97 and 23.98 refresh rate

[Ville Syrjälä]

On Thu, Oct 08, 2015 at 03:39:26PM +0300, Jani Nikula wrote:
> On Thu, 08 Oct 2015, Ville Syrjälä <ville.syrjala at linux.intel.com> wrote:
> > On Wed, Oct 07, 2015 at 02:38:29PM -0700, clinton.a.taylor at intel.com wrote:
> >> From: Clint Taylor <clinton.a.taylor at intel.com>
> >> 
> >> The TMDS_296M define was computing as 296704 but the mode->clock is
> >> 296700 as defined by EDID. Adjusted define to allow correct detection
> >> of the need to program the correct N value for 29.97 and 23.98 refresh
> >> rate.
> >> 
> >> Signed-off-by: Clint Taylor <clinton.a.taylor at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/intel_audio.c |    2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
> >> index 56c2f54..419c979 100644
> >> --- a/drivers/gpu/drm/i915/intel_audio.c
> >> +++ b/drivers/gpu/drm/i915/intel_audio.c
> >> @@ -75,7 +75,7 @@ static const struct {
> >>  
> >>  /* HDMI N/CTS table */
> >>  #define TMDS_297M 297000
> >> -#define TMDS_296M DIV_ROUND_UP(297000 * 1000, 1001)
> >> +#define TMDS_296M 296700
> >
> > Hmm. I think we might want to fix up the mode instead. Let me post a few
> > patches, and let's see what people think...
> 
> We might actually want to queue this up for v4.3 as the immediate fix,
> as I feel it's doubtful your other patches will make it to v4.3.
> 
> If Someone(tm) provided their r-b that is.

Except this is wrong if the mode came from the CEA/HDMI mode list as
opposed from the EDID detailed timings.

-- 
Ville Syrjälä
Intel OTC