[Intel-gfx] [PATCH 0/4] drm/amd/display: stop using drm_edid_override_connector_update()

[Jani Nikula]

On Tue, 29 Aug 2023, Alex Hung <alex.hung at amd.com> wrote:
> On 2023-08-29 11:03, Jani Nikula wrote:
>> On Tue, 29 Aug 2023, Jani Nikula <jani.nikula at intel.com> wrote:
>>> On Tue, 29 Aug 2023, Alex Deucher <alexdeucher at gmail.com> wrote:
>>>> On Tue, Aug 29, 2023 at 6:48 AM Jani Nikula <jani.nikula at intel.com> wrote:
>>>>>
>>>>> On Wed, 23 Aug 2023, Jani Nikula <jani.nikula at intel.com> wrote:
>>>>>> On Tue, 22 Aug 2023, Alex Hung <alex.hung at amd.com> wrote:
>>>>>>> On 2023-08-22 06:01, Jani Nikula wrote:
>>>>>>>> Over the past years I've been trying to unify the override and firmware
>>>>>>>> EDID handling as well as EDID property updates. It won't work if drivers
>>>>>>>> do their own random things.
>>>>>>> Let's check how to replace these references by appropriate ones or fork
>>>>>>> the function as reverting these patches causes regressions.
>>>>>>
>>>>>> I think the fundamental problem you have is conflating connector forcing
>>>>>> with EDID override. They're orthogonal. The .force callback has no
>>>>>> business basing the decisions on connector->edid_override. Force is
>>>>>> force, override is override.
>>>>>>
>>>>>> The driver isn't even supposed to know or care if the EDID originates
>>>>>> from the firmware loader or override EDID debugfs. drm_get_edid() will
>>>>>> handle that for you transparently. It'll return the EDID, and you
>>>>>> shouldn't look at connector->edid_blob_ptr either. Using that will make
>>>>>> future work in drm_edid.c harder.
>>>>>>
>>>>>> You can't fix that with minor tweaks. I think you'll be better off
>>>>>> starting from scratch.
>>>>>>
>>>>>> Also, connector->edid_override is debugfs. You actually can change the
>>>>>> behaviour. If your userspace, whatever it is, has been written to assume
>>>>>> connector forcing if EDID override is set, you *do* have to fix that,
>>>>>> and set both.
>>>>>
>>>>> Any updates on fixing this, or shall we proceed with the reverts?
>
> There is a patch under internal reviews. It removes calls edid_override 
> and drm_edid_override_connector_update as intended in this patchset but 
> does not remove the functionality.

While I am happy to hear there's progress, I'm somewhat baffled the
review is internal. The commits that I suggested to revert were also
only reviewed internally, as far as I can see... And that's kind of the
problem.

Upstream code should be reviewed in public.


BR,
Jani.


>
> With the patch. both following git grep commands return nothing in 
> amd-staging-drm-next.
>
> $ git grep drm_edid_override_connector_update -- drivers/gpu/drm/amd
> $ git grep edid_override -- drivers/gpu/drm/amd
>
> Best regards,
> Alex Hung
>
>>>>
>>>> What is the goal of the reverts?  I don't disagree that we may be
>>>> using the interfaces wrong, but reverting them will regess
>>>> functionality in the driver.
>>>
>>> The commits are in v6.5-rc1, but not yet in a release. No user depends
>>> on them yet. I'd strongly prefer them not reaching v6.5 final and users.
>> 
>> Sorry for confusion here, that's obviously come and gone already. :(
>> 
>>> The firmware EDID, override EDID, connector forcing, the EDID property,
>>> etc. have been and somewhat still are a hairy mess that we must keep
>>> untangling, and this isn't helping.
>>>
>>> I've put in crazy amounts of work on this, and I've added kernel-doc
>>> comments about stuff that should and should not be done, but they go
>>> unread and ignored.
>>>
>>> I really don't want to end up having to clean this up myself before I
>>> can embark on further cleanups and refactoring.
>>>
>>> And again, if the functionality in the driver depends on conflating two
>>> things that should be separate, it's probably not such a hot idea to let
>>> it reach users either. Even if it's just debugfs.
>>>
>>>
>>> BR,
>>> Jani.
>> 

-- 
Jani Nikula, Intel Open Source Graphics Center