Re: [RFC v2 0/1] drm/connector: Add support for privacy-screen properties

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 5/12/20 4:20 PM, Pekka Paalanen wrote:
> On Tue, 12 May 2020 10:18:31 +0200
> Hans de Goede <hdegoede@redhat.com> wrote:
> 
>> Hi,
>>
>> On 5/11/20 9:55 PM, Rajat Jain wrote:
>>> Hi Hans,
>>>
>>> On Mon, May 11, 2020 at 10:47 AM Hans de Goede <hdegoede@redhat.com <mailto:hdegoede@redhat.com>> wrote:
>>>
>>>      Hi All,
>>>
>>>      This RFC takes Rajat's earlier patch for adding privacy-screen properties
>>>      infra to drm_connector.c and then adds the results of the discussion from
>>>      the "RFC: Drm-connector properties managed by another driver / privacy
>>>      screen support" mail thread on top, hence the v2.
>>>
>>>
>>> Thank you so much for doing this. I was following the said discussion and eventually it became quite complex for me to understand and follow :-)
>>
>> I hope the new doc text makes things clear again?
>>
>>
>>>      The most important thing here is big kernel-doc comment which gets added in
>>>      the first patch-chunk modifying drm_connector.c, this summarizes, or at
>>>      least tries to summarize, the conclusions of our previous discussion on
>>>      the userspace API and lays down the ground rules for how the 2 new
>>>      "privacy-screen sw-state" and  "privacy-screen hw-state" properties are
>>>      to be used both from the driver side as well as from the userspace side.
>>>
>>>      Other then that this modifies Rajat's patch to add 2 properties instead
>>>      of one, without much other changes.
>>>
>>>      Rajat, perhaps you can do a new version of your patch-set integration /
>>>      using this version of the properties and then if everyone is ok with
>>>      the proposed userspace API Jani can hopefully merge the whole set
>>>      through the i915 tree sometime during the 5.9 cycle.
>>>
>>>
>>> SGTM. I have actually moved to working on something else now, so I will most likely wait for this patch to get merged, before rebasing my other / remaining patches on top of that.
>>
>> We have the rule that code like this will not be merged until it has at least
>> one in kernel user. I plan to eventually use this too, but that is still
>> a while away as I first need to write a lcdshadow subsystem which the
>> thinkpad_acpi code can then use to register a lcdshadow device; and when
>> that all is in place, then I can hook it up on the drm code.
> 
> Hi,
> 
> I believe this falls under "new UAPI" rules, because this is adding new
> KMS properties. Hence an in-kernel user is not enough:
> 
> https://www.kernel.org/doc/html/latest/gpu/drm-uapi.html#open-source-userspace-requirements

Hmm, I believe that that mostly applies to new DRI (ioclt) interfaces for
submitting rendering commands to new GPUs and other complex new APIs and
not necessarily to introducing new properties.    Also note that all
properties are exported under X through Xrandr, at least reading them,
not sure about setting them.

Anyways I do plan to write some mutter code to test my lcdshadow subsys <->
DRM driver integration when that is all more then just vaporware. But I
would prefer for Rajat's series to land before that so that I can build
on top of it.

Regards,

Hans

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