[PATCH 3/3] drm/i915/edp: eDP Data Overrride

[Kandpal, Suraj]

> -----Original Message-----
> From: Jani Nikula <jani.nikula at linux.intel.com>
> Sent: Monday, July 28, 2025 6:30 PM
> To: Kandpal, Suraj <suraj.kandpal at intel.com>; intel-xe at lists.freedesktop.org;
> intel-gfx at lists.freedesktop.org
> Cc: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>; Kandpal, Suraj
> <suraj.kandpal at intel.com>
> Subject: Re: [PATCH 3/3] drm/i915/edp: eDP Data Overrride
> 
> On Fri, 25 Jul 2025, Suraj Kandpal <suraj.kandpal at intel.com> wrote:
> > We need override certain link rates in favour of the next available
> > higher link rate. The Link rates that need to be overridden are
> > indicated by a mask in VBT. To make sure these modes are skipped we
> > don't add them in them in the sink rates array.
> >
> > --v2
> > -Update the link rates after we have a final set of link rates [Ankit]
> > -Break this patch up [Ankit] -Optimize the assingment during loop
> > [Ankit]
> >
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c
> > b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 54d88f24b689..040344949b8f 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -4277,6 +4277,23 @@ static void intel_edp_mso_init(struct intel_dp
> *intel_dp)
> >  	intel_dp->mso_pixel_overlap = mso ? info->mso_pixel_overlap : 0;  }
> >
> > +static void
> > +intel_edp_set_data_override_rates(struct intel_dp *intel_dp) {
> > +	struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
> > +	int *sink_rates = intel_dp->sink_rates;
> > +	int i, j = 0;
> > +
> > +	for (i = 0; i < intel_dp->num_sink_rates; i++) {
> > +		if (intel_bios_need_edp_data_override(encoder->devdata,
> > +						      intel_dp->sink_rates[i]))
> > +			continue;
> > +
> > +		sink_rates[j++] = intel_dp->sink_rates[i];
> > +	}
> > +	intel_dp->num_sink_rates = j;
> > +}
> > +
> >  static void
> >  intel_edp_set_sink_rates(struct intel_dp *intel_dp)  { @@ -4327,6
> > +4344,8 @@ intel_edp_set_sink_rates(struct intel_dp *intel_dp)
> >  		intel_dp->use_rate_select = true;
> >  	else
> >  		intel_dp_set_sink_rates(intel_dp);
> > +
> > +	intel_edp_set_data_override_rates(intel_dp);
> 
> This can lead to no rates with a broken VBT, and so far we've taken care to
> always have the fallback in there.

I can add a hweight32(edp_data_rate_override) >= 11 and skip this entirely since that would mean the
OEM has set all the sink rates to be overridden leaving no other option.
I can do the skip sliently or add a drm_dbg or drm_err which one would you prefer.

Regards,
Suraj Kandpal
 
> 
> BR,
> Jani.
> 
> >  }
> >
> >  static bool
> 
> --
> Jani Nikula, Intel