Re: [PATCH 1/9] drm: Add gamma mode property

From: Pekka Paalanen <ppaalanen@gmail.com>
To: "Shankar, Uma" <uma.shankar@intel.com>
Cc: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"Modem, Bhanuprakash" <bhanuprakash.modem@intel.com>
Subject: Re: [PATCH 1/9] drm: Add gamma mode property
Date: Thu, 3 Jun 2021 11:05:27 +0300	[thread overview]
Message-ID: <20210603110527.39ead45e@eldfell> (raw)
In-Reply-To: <33e9b79a413346309519f2a2499de367@intel.com>

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On Wed, 2 Jun 2021 20:18:19 +0000
"Shankar, Uma" <uma.shankar@intel.com> wrote:

> > -----Original Message-----
> > From: Pekka Paalanen <ppaalanen@gmail.com>
> > Sent: Wednesday, June 2, 2021 2:40 PM
> > To: Shankar, Uma <uma.shankar@intel.com>
> > Cc: intel-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; Modem,
> > Bhanuprakash <bhanuprakash.modem@intel.com>
> > Subject: Re: [PATCH 1/9] drm: Add gamma mode property
> > 
> > On Tue,  1 Jun 2021 16:11:27 +0530
> > Uma Shankar <uma.shankar@intel.com> wrote:
> >   
> > > Add a gamma mode property to enable various kind of gamma modes
> > > supported by platforms like: Interpolated, Split, Multi Segmented,
> > > Logarithmic etc. Userspace can get this property and should be able to
> > > get the platform capabilities wrt various gamma modes possible and the
> > > possible ranges.
> > >
> > > It can select one of the modes exposed as blob_id as an enum and set
> > > the respective mode.
> > >
> > > It can then create the LUT and send it to driver using already
> > > available GAMMA_LUT property as blob.
> > >
> > > Note: This is based on design by Ville and is being carried forward
> > > based on his original idea.
> > >
> > > Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> > > ---
> > >  drivers/gpu/drm/drm_atomic_uapi.c |  5 +++
> > > drivers/gpu/drm/drm_color_mgmt.c  | 75 +++++++++++++++++++++++++++++++
> > >  include/drm/drm_color_mgmt.h      |  8 ++++
> > >  include/drm/drm_crtc.h            | 14 ++++++
> > >  include/uapi/drm/drm_mode.h       | 43 ++++++++++++++++++
> > >  5 files changed, 145 insertions(+)

...

> > Hi,
> > 
> > where is the UAPI documentation for this new GAMMA_MODE?
> > As a userspace dev, I have no idea what to do with the above based on what's
> > written here.  
> 
> Got that, I will add more details on the UAPI usage to make things a bit clearer.
> 
> > Also, reading the description of DRM_CLIENT_CAP_ADVANCE_GAMMA_MODES in
> > patch 5/9, what difference does it make whether userspace sets or does not set that
> > cap? I don't understand the implications from the description.  
> 
> The reason we have this Client caps is to have it co-exist with legacy crtc color properties.
> The idea is that driver will describe the h/w luts to userspace through GAMMA_MODE UAPI,
> but the actual lut samples will still be sent through the legacy GAMMA_LUT UAPI. This client
> cap will help distinguish between legacy and this new implementation.
> 
> I will add more details in the UAPI description to avoid ambiguity and explain the rationale and
> usage of this UAPI.
> 
> Thanks Pekka for the looking into the series and the initial feedback.

Thanks a lot, will be interesting to read those docs.
pq

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