> -----Original Message-----
> From: Nautiyal, Ankit K <ankit.k.nautiyal@xxxxxxxxx>
> Sent: Friday, July 8, 2022 3:36 PM
> To: Murthy, Arun R <arun.r.murthy@xxxxxxxxx>; intel-
> gfx@xxxxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH] drm/i915/hdmi: Prune modes that require
> HDMI2.1 FRL
>
> Hi Arun,
>
> Thanks for the comments.
>
> Please find my response inline.
>
> On 7/8/2022 9:30 AM, Murthy, Arun R wrote:
> >
> >> -----Original Message-----
> >> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf
> >> Of Ankit Nautiyal
> >> Sent: Thursday, July 7, 2022 10:57 AM
> >> To: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> >> Subject: [PATCH] drm/i915/hdmi: Prune modes that require
> >> HDMI2.1 FRL
> >>
> >> HDMI2.1 requires some higher resolution video modes to be enumerated
> >> only if HDMI2.1 Fixed Rate Link (FRL) is supported.
> >> Current platforms do not support FRL transmission so prune modes that
> >> require HDMI2.1 FRL.
> >>
> > If the hardware doesn't support FRL then it basically blocks HDMI2.1
> feature.
> > Then it wont be possible to use any resolution above 4k60 is it?
>
>
> Yes right. As I understand, the HDMI2.1a supersedes HDMI2.0b, and so the
>
> platforms supporting HDMI2.0 must now pass the HDMI2.1 CTS.
> The HDMI2.1a spec introduces Marketing Feature names for 4K100, 4K120,
> 8k@50, 8k@60 with suffix A, and B.
> Suffix A meaning mode supported without compression, and B meaning,
> mode supported with compression.
>
> There are CTS tests that expect these modes not to be enumerated, if the
> source does support the given requirements.
>
>
Thanks for the clarification.
> >
> >> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
> >> ---
> >> drivers/gpu/drm/i915/display/intel_hdmi.c | 21
> +++++++++++++++++++++
> >> 1 file changed, 21 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c
> >> b/drivers/gpu/drm/i915/display/intel_hdmi.c
> >> index ebd91aa69dd2..93c00b61795f 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> >> @@ -1974,6 +1974,20 @@ intel_hdmi_mode_clock_valid(struct
> >> drm_connector *connector, int clock,
> >> return status;
> >> }
> >>
> >> +/*
> >> + * HDMI2.1 requires higher resolution modes like 8k60, 4K120 to be
> >> + * enumerated only if FRL is supported. Platforms not supporting FRL
> >> + * must prune these modes.
> >> + */
> >> +static bool
> >> +hdmi21_frl_quirk(int dotclock, bool frl_supported) {
> >> + if (dotclock >= 600000 && !frl_supported)
> >> + return true;
> >> +
> >> + return false;
> >> +}
> >> +
> >> static enum drm_mode_status
> >> intel_hdmi_mode_valid(struct drm_connector *connector,
> >> struct drm_display_mode *mode) @@ -2001,6 +2015,13
> @@
> >> intel_hdmi_mode_valid(struct drm_connector *connector,
> >> clock *= 2;
> >> }
> >>
> >> + /*
> >> + * Current Platforms do not support HDMI2.1 FRL mode of
> >> transmission,
> >> + * so prune the modes that require FRL.
> >> + */
> >> + if (hdmi21_frl_quirk(clock, false))
> >> + return MODE_BAD;
> >> +
> > Instead of setting this frl_supported as false, can we get this info
> > from hardware, so that when our hardware supports it later it would be
> easy to enable this.
>
> We can have something like:
>
> src_supports_frl()
>
> {
>
> /* FRL not supported in
>
> return false;
>
> }
>
Yes something like this looks good. It would be a good design to judge this based on the
Display version.
Thanks and Regards,
Arun R Murthy
--------------------
