Re: [RESEND] drm/i915/hdmi: Poll for 200 msec for TMDS_Scrambler_Status

["Nautiyal, Ankit K" <ankit.k.nautiyal@intel.com>]

On 2/14/2026 9:47 PM, Jérôme Tollet wrote:
> Hi Ville, Ankit,
>
> Update on testing (Feb 14):
> After isolated testing of each patch on kernel 6.18.7, I can now
> definitively confirm:
>
> - SCDC polling patch ALONE: Works perfectly ✓
> - delay patch (150ms) ALONE: Screen remains black ✗
> - Both patches together: Works (but delay is unnecessary)
>
> This definitively answers the question: approach #1 (Generic SCDC
> polling after port enable) is the correct solution. The v2 delay patch
> is NOT needed and should be disregarded.
>
> The SCDC polling aligns with HDMI 2.0 spec requirements and Windows
> behavior, making it the proper generic solution.


Thanks Jerome for testing.

Lets have all discussion in the original thread on the patch [1].

It seems your recent mails are on a separate thread.


Regards,


Ankit


[1] 
https://lore.kernel.org/intel-xe/73e0de50-b7e3-4315-ab81-0a3ecebc2363@intel.com/



> Sorry for any confusion from my earlier messages.
>
> Thanks,
> Jerome
>
> Le sam. 7 févr. 2026 à 04:14, Jérôme Tollet <jerome.tollet@gmail.com> a écrit :
>> Hi Ville, Ankit,
>>
>> Gentle ping on this thread - it's been about 10 days since my last
>> message in the thread (Jan 28).
>>
>> To recap, we have three potential approaches for this fix:
>> 1. Generic SCDC polling after port enable (current patch) - aligns
>> with Windows behavior
>> 2. Panel-specific quirk for affected displays (Cisco Desk Pro in my case)
>> 3. Fixed delay after SCDC config (my v2 patch from Jan 14)
>>
>> Testing showed the delay works at any placement in the modeset
>> sequence, suggesting this is a timing issue rather than
>> operation-specific.
>> I'm happy to implement whichever approach you prefer. Please let me
>> know which direction you'd like me to take this.
>>
>> Thanks,
>> Jerome
>>
>>
>> Le mer. 28 janv. 2026 à 15:42, Jérôme Tollet <jerome.tollet@gmail.com> a écrit :
>>> Hi Ville,
>>> Following Ankit's response on January 21st where he suggested
>>> considering a panel-specific quirk instead of a generic solution, I
>>> wanted to get your input on the preferred approach.
>>> As a reminder, testing showed the delay works at any placement in the
>>> modeset sequence (all 4 test positions succeeded), suggesting this is
>>> a timing issue rather than being tied to a specific operation.
>>>
>>> Three approaches are available:
>>> 1. Generic SCDC polling after port enable - aligns with Windows
>>> behavior which also performs ~200ms SCDC poll post-enable
>>> 2. Panel-specific quirk for affected displays (Cisco Desk Pro in my case)
>>> 3. Fixed delay after SCDC config (my v2 patch from Jan 14)
>>>
>>> I'm happy with any approach that gets merged.
>>>
>>> Thanks
>>> Jerome