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Subject: Re: [PATCH v4 09/17] drm/uAPI: Add "active color range" drm property
 as feedback for userspace
To:     Pekka Paalanen <ppaalanen@gmail.com>
Cc:     sunpeng.li@amd.com, intel-gfx@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        airlied@linux.ie, amd-gfx@lists.freedesktop.org,
        tzimmermann@suse.de, rodrigo.vivi@intel.com,
        alexander.deucher@amd.com, christian.koenig@amd.com
References: <20210618091116.14428-1-wse@tuxedocomputers.com>
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 <5947f768-dd87-6b39-ecfc-b7c4aaa88aca@tuxedocomputers.com>
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From:   Werner Sembach <wse@tuxedocomputers.com>
Message-ID: <fe83dcd2-889d-f9de-fc4e-b25b1887cb80@tuxedocomputers.com>
Date:   Wed, 23 Jun 2021 13:19:41 +0200
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Am 23.06.21 um 13:14 schrieb Pekka Paalanen:
> On Wed, 23 Jun 2021 12:17:40 +0200
> Werner Sembach <wse@tuxedocomputers.com> wrote:
>
>> Am 23.06.21 um 09:32 schrieb Pekka Paalanen:
>>> On Tue, 22 Jun 2021 11:48:52 +0000
>>> Simon Ser <contact@emersion.fr> wrote:
>>>  
>>>> On Tuesday, June 22nd, 2021 at 11:50, Werner Sembach <wse@tuxedocomputers.com> wrote:
>>>>  
>>>>> Unknown is when no monitor is connected or is when the
>>>>> connector/monitor is disabled.    
>>>> I think the other connector props (link-status, non-desktop, etc) don't
>>>> have a special "unset" value, and instead the value is set to a random
>>>> enum entry. User-space should ignore the prop on these disconnected
>>>> connectors anyways.  
>>> That sounds fine to me.  
>> Currently the only case for "not applicable" is when the monitor is
>> disconnected, but sicne the properties are so interdependent, there
>> might be a case in the future where e.g. a color format that has no
>> differentiation between full and limited arises. When there is no
>> special unset/not applicable option, the userspace has to know
>> exactly when an option is valid or not, possible requiring additional
>> logic.
>>
>> Setting a "not applicable" value allows userspace to be more dumb,
>> without much hassle on the kernelspace side.
> That's a good point too. So "not applicable" would be a value, but
> "unknown" would not be.
Ok, I have already renamed the "unknown" option to "not applicable" in my next revision (not yet posted to the mailing
list).
>
>
> Thanks,
> pq