Re: [Intel-gfx] [PATCH] drm/i915/display/dp: Remove support for UHBR13.5

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 27 Jun 2023, "Murthy, Arun R" <arun.r.murthy@intel.com> wrote:
>> -----Original Message-----
>> From: Nikula, Jani <jani.nikula@intel.com>
>> Sent: Monday, June 26, 2023 6:02 PM
>> To: Murthy, Arun R <arun.r.murthy@intel.com>; intel-
>> gfx@lists.freedesktop.org
>> Cc: Deak, Imre <imre.deak@intel.com>; Kahola, Mika
>> <mika.kahola@intel.com>
>> Subject: RE: [PATCH] drm/i915/display/dp: Remove support for UHBR13.5
>>
>> On Thu, 22 Jun 2023, "Murthy, Arun R" <arun.r.murthy@intel.com> wrote:
>> >> -----Original Message-----
>> >> From: Nikula, Jani <jani.nikula@intel.com>
>> >> Sent: Wednesday, June 21, 2023 2:27 PM
>> >> To: Murthy, Arun R <arun.r.murthy@intel.com>; intel-
>> >> gfx@lists.freedesktop.org
>> >> Cc: Deak, Imre <imre.deak@intel.com>; Kahola, Mika
>> >> <mika.kahola@intel.com>; Murthy, Arun R <arun.r.murthy@intel.com>
>> >> Subject: Re: [PATCH] drm/i915/display/dp: Remove support for UHBR13.5
>> >>
>> >> On Tue, 20 Jun 2023, Arun R Murthy <arun.r.murthy@intel.com> wrote:
>> >> > As per the DP2.1 Spec support for UHBR13.5 is optional. Hence
>> >> > removing the support for UHBR13.5
>> >>
>> >> That's just not a proper rationale. Please explain.
>> >>
>> > Programming for UHBR10 and UHBR20 is similar compared to UHBR13.5 As
>> > of now we have validated 10Gbps and 20Gbps. The spec also points out
>> > when 20Gbps is supported 13.5Gbps is optional so we have not
>> validated/implemented the UHBR13.5 Now we have the DP2.1 compatible
>> panel is market, expecting users can come up with UHBR13.5 not working.
>> Hence removing the support for 13.5Gbps for now.
>> > Maybe once we have support for UHBR13.5 in the driver we can enable
>> this.
>>
>> What's missing?
>>
> Port clock programming, pll values differs.
> This table has been in place but some corrections/recheck required.

Can we do that instead please?

I accidentally stumbled on the relevant gitlab issue [1] (please add
this kind of information up front in the future), so we have a reporter
that could test the fixes.

BR,
Jani.


[1] https://gitlab.freedesktop.org/drm/intel/-/issues/8686

>
> Thanks and Regards,
> Arun R Murthy
> --------------------

-- 
Jani Nikula, Intel Open Source Graphics Center