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Subject: Re: [PATCH 1/6] include/drm: color_mgmt: Add enum labels
To:     =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>,
        Christoph Manszewski <c.manszewski@samsung.com>
Cc:     linux-samsung-soc@vger.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Maxime Ripard <maxime.ripard@bootlin.com>,
        Seung-Woo Kim <sw0312.kim@samsung.com>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        David Airlie <airlied@linux.ie>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Kukjin Kim <kgene@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Sean Paul <sean@poorly.run>,
        linux-arm-kernel@lists.infradead.org,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        'Hans Verkuil' <hans.verkuil@cisco.com>
From:   Andrzej Hajda <a.hajda@samsung.com>
Message-ID: <b9cfbae1-b24e-96bf-f3b0-ff6d25cd16bb@samsung.com>
Date:   Fri, 18 Jan 2019 15:34:18 +0100
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+CC: Hans

On 17.01.2019 20:47, Ville Syrjälä wrote:
> On Fri, Dec 14, 2018 at 01:10:16PM +0100, Christoph Manszewski wrote:
>> Range setting makes sense for YCbCr and RGB buffers. Current
>> drm_color_range enum labels suggest use with YCbCr buffers.
>> Create enum labels without colorspace specification.
>>
>> Signed-off-by: Christoph Manszewski <c.manszewski@samsung.com>
>> ---
>>  include/drm/drm_color_mgmt.h | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
>> index 90ef9996d9a4..52f6d5221a0d 100644
>> --- a/include/drm/drm_color_mgmt.h
>> +++ b/include/drm/drm_color_mgmt.h
>> @@ -62,6 +62,8 @@ enum drm_color_range {
>>  	DRM_COLOR_YCBCR_LIMITED_RANGE,
>>  	DRM_COLOR_YCBCR_FULL_RANGE,
>>  	DRM_COLOR_RANGE_MAX,
>> +	DRM_COLOR_LIMITED_RANGE = DRM_COLOR_YCBCR_LIMITED_RANGE,
>> +	DRM_COLOR_FULL_RANGE = DRM_COLOR_YCBCR_FULL_RANGE,
> These enum values don't mean anything really. The strings are what
> matter for the uapi.
>
> The default for YCbCr needs to be limited range, the default for RGB
> needs to be full range. So I think this would really require a separate
> prop for each.
>
> But is there an actual usecase for this stuff?


Yes, for example HDMI path (Display Controller and HDMI encoder) in
Exynos5433 works on RGB buffers and do not perform any conversion if the
output is also RGB, on the other side CEA861 specs says that in case of
CEA modes output RGB should be in limited range, in case of non CEA
modes it should be full range.

The idea was to allow userspace to check (atomic_check) which ranges are
acceptable in given mode and to set desired one if possible.

Any better solution is welcome?


Regards

Andrzej


>
>>  };
>>  
>>  int drm_plane_create_color_properties(struct drm_plane *plane,
>> -- 
>> 2.7.4
>>
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