[RFC 0/1] Color space conversion uapi part2

[Shankar, Uma]

>-----Original Message-----
>From: dri-devel [mailto:dri-devel-bounces at lists.freedesktop.org] On Behalf Of
>Alexandru-Cosmin Gheorghe
>Sent: Monday, February 26, 2018 10:18 PM
>To: Ville Syrjälä <ville.syrjala at linux.intel.com>; Shankar, Uma
><uma.shankar at intel.com>
>Cc: airlied at linux.ie; nd at arm.com; liviu.dudau at arm.com; dri-
>devel at lists.freedesktop.org; mihail.atanassov at arm.com
>Subject: Re: [RFC 0/1] Color space conversion uapi part2
>
>On Mon, Feb 26, 2018 at 06:04:37PM +0200, Ville Syrjälä wrote:
>> On Mon, Feb 26, 2018 at 03:59:21PM +0000, Alexandru Gheorghe wrote:
>> > This is an attempt to revive the color space conversation that
>> > started here [1] and was materialized with the color encoding and
>> > color range properties for converting YUV2RGB, the last version of
>> > this patch series is here [2].
>> >
>> > However, we still need a way of specifing the color gamut and
>> > transfer
>> > function(gamma) for a given plane, in order to be sure that the
>> > blending is done in the same domain space, which is not an issue for
>> > similar gammuts, but not so good when mixing wider gamuts like
>> > Rec2020 and DCI-P3 with narrow ones.
>> >
>> > In consequence, the userspace needs to control what is the color
>> > gamut used for blending.
>> >
>> > On Mali DP hardware, a complete color processing pipeline for a
>> > plane looks like this:
>> >
>> > YUV2RGB -> DEGAMA -> RGB2RGB(Gammut conv) -> GAMMA.
>> >
>> > Of course, depending on hardware generation some of this elements
>> > are not present or disabled if we are dealing with a RGB buffer
>> > already in linear space. But it's up to the usperspace to decide
>> > what it wants when the hardware doesn't provide full support for its needs.
>> >
>> > What this patchset proposes is to add plane degamma, ctm and gamma
>> > properties to be applied in this order after the yuv2rgb conversion
>> > specified by the color encoding property[2]. We already have this
>> > sort of pipeline(degamma, ctm, gamma) at the other end of a CRTC, so
>> > it wouldn't be a totaly new interface for userspaces to figure it
>> > out how to use.
>> >
>> > There are still some things to be done before getting this patchset
>> > in mergeable shape like: mali-dp driver implementation, real
>> > userspace (drm_hwcomposer is the likely candidate here, but I'm open
>> > to suggestions here), reuse some of the code for both crtc and plane.
>> >
>> > But first, I would like to see what everybody things about this
>> > idea, or if it has a different perspective of how this should be handled.
>> >
>> > [1] https://lkml.org/lkml/2017/3/16/681
>> > [2] https://www.spinics.net/lists/intel-gfx/msg156211.html
>>
>> How is this related to eg.
>> https://patchwork.freedesktop.org/series/30876/ ?
>I wasn't aware of this patchset. Thanks.
>Same idea, almost identical implementation, I suppose it's true that some topics
>pop-up periodically.
>
>@Uma, is there an updated patchset anywhere that I missed.
>

Hi Alexandru,
The series which Ville highlighted (https://patchwork.freedesktop.org/series/30876/)
was published long back, but due to lack of userspace consumers (hwc, Weston etc.), 
cannot be considered for merge. We are trying to get that implemented at Intel (still
little far away though)

In principal, people were ok with this idea of having color correction support at plane
level for efficient blending.

Regards,
Uma Shankar
>>
>> >
>> > Mihail Atanassov (1):
>> >   drm: Add per-plane color management
>> >
>> >  drivers/gpu/drm/drm_atomic.c        | 28 ++++++++++++++
>> >  drivers/gpu/drm/drm_atomic_helper.c |  9 +++++
>> >  drivers/gpu/drm/drm_color_mgmt.c    | 76 +++++++++++++++++++++++++++-
>---------
>> >  include/drm/drm_color_mgmt.h        |  5 +++
>> >  include/drm/drm_mode_config.h       | 20 +++++-----
>> >  include/drm/drm_plane.h             |  8 ++++
>> >  6 files changed, 117 insertions(+), 29 deletions(-)
>> >
>> > --
>> > 2.7.4
>> >
>> > _______________________________________________
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>> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
>> --
>> Ville Syrjälä
>> Intel OTC
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