[PATCH] Revert "drm/msm/dp: use drm_bridge_hpd_notify() to report HPD status changes"

[Abhinav Kumar]

On 2/28/2024 5:28 AM, Johan Hovold wrote:
> On Wed, Feb 28, 2024 at 01:08:04PM +0200, Dmitry Baryshkov wrote:
>> On Wed, 28 Feb 2024 at 11:50, Johan Hovold <johan at kernel.org> wrote:
>>>
>>> On Tue, Feb 27, 2024 at 02:11:56PM -0800, Abhinav Kumar wrote:
>>>> On 2/27/2024 2:08 PM, Dmitry Baryshkov wrote:
>>>>> This reverts commit e467e0bde881 ("drm/msm/dp: use
>>>>> drm_bridge_hpd_notify() to report HPD status changes").
>>>>>
>>>>> The commit changed the way how the MSM DP driver communicates
>>>>> HPD-related events to the userspace. The mentioned commit made some of
>>>>> the HPD events being reported earlier. This way userspace starts poking
>>>>> around. It interacts in a bad way with the dp_bridge_detect and the
>>>>> driver's state machine, ending up either with the very long delays
>>>>> during hotplug detection or even inability of the DP driver to report
>>>>> the display as connected.
>>>>>
>>>>> A proper fix will involve redesigning of the HPD handling in the MSM DP
>>>>> driver. It is underway, but it will be intrusive and can not be thought
>>>>> about as a simple fix for the issue. Thus, revert the offending commit.
>>>>
>>>> Yes, for fixing this on 6.9 I am fine with this.
>>>
>>> Since this is a regression in 6.8-rc1, I hope you meant to say 6.8 here?
>>
>> In the worst case it will land to 6.8.x via the stable tree process.
> 
> This is a fix for a user-visible regression that was reported formally
> two weeks ago and informally (e.g. to you) soon after rc1 came out, and
> which now also has an identified cause and an analysis of the problem.
> And we're at rc6 so there should be no reason to delay fixing this (e.g.
> even if you want to run some more tests for a couple of days).
> 

Yup, we landed it in msm-fixes now, so this will go as a late -fixes PR 
for 6.8.


> Johan