Design review request: DRM color manager

[Sharma, Shashank]

Gentle reminder

Regards
Shashank 
-----Original Message-----
From: Sharma, Shashank 
Sent: Friday, April 18, 2014 12:01 PM
To: intel-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org; Ville Syrjälä; Thierry Reding; Alex Deucher; Sean Paul; robdclark at gmail.com
Cc: Shankar, Uma; Korjani, Vikas; Jindal, Sonika; Mukherjee, Indranil; Cn, Ramakrishnan
Subject: Design review request: DRM color manager

Hi All,

Based on all the previous feedbacks, we have done the design changes in previous color manager implementation.
This new design addresses following previous comments / suggestions / requirements: 

1. HW agnostic design, so each driver can register its own capabilities, and own color correction methods. 
2. DRM property based interface design, so can be plugged in with atomic modeset() and other DRM implementation. 
3. Single interface for all color correction related properties.

Please find the design document attached with the mail. I would request you all to have a look, and help us to freeze the design by provide suggestions, design changes and improvements needs etc.
Once we agree on the design, we will start the implementation. 

Regards
Shashank
-----Original Message-----
From: Thierry Reding [mailto:thierry.reding at gmail.com]
Sent: Tuesday, February 25, 2014 5:12 PM
To: Alex Deucher
Cc: Ville Syrjälä; intel-gfx at lists.freedesktop.org; Shankar, Uma; dri-devel at lists.freedesktop.org; Sharma, Shashank
Subject: Re: [Intel-gfx] [PATCH 0/6] Intel Color Manager Framework

On Fri, Feb 21, 2014 at 10:41:14AM -0500, Alex Deucher wrote:
> On Fri, Feb 21, 2014 at 9:46 AM, Ville Syrjälä 
> <ville.syrjala at linux.intel.com> wrote:
> > On Fri, Feb 21, 2014 at 02:20:24PM +0000, Sharma, Shashank wrote:
> >> Hi Ville,
> >>
> >> Thanks for your time and comments.
> >> I can understand two basic problems what you see in this implementation:
> >>
> >> 1.  The most important issue from my POV is that it can't be part of the atomic modeset.
> >> 2.  it make the whole API inconsistent.
> >>
> >> I am not sure if its good to block all current implementation because we have thought something for this in atomic modeset.
> >> I think even in atomic modeset we need the core implementation like this, but the interface would be different, which might come in from of a DRM property.
> >> So at that time we can use this core implementation as it is, only the interfaces/framework needs to be changed.
> >>
> >> In this way we can always go ahead with a current implementation, and can just change the interfaces to fit in to the final interface like DRM property in atomic modeset.
> >> Or you can suggest us the expected interface, and we can work on modifying that as per expectation.
> >
> > The exptected interface will be range properties for stuff like 
> > brightness, contrast etc. controls. There are already such things as 
> > connector properties, but we're going to want something similar as 
> > plane or crtc properties. One thing that worries me about such 
> > properties though is whether we can make them hardware agnostic and 
> > yet allow userspace precise control over the final image. That is, 
> > if we map some fixed input range to a hardware specific output 
> > range, userspace can't know how the actual output will change when 
> > the input changes. On the other hand if the input is hardware 
> > specific, userspace can't know what value to put in there to get the expected change on the output side.
> >
> > For bigger stuff like CSC matrices and gamma ramps we will want to 
> > use some reasonably well defined blobs. Ie. the internal strucuture 
> > of the blob has to be documented and it shouldn't contain more than necessary.
> > Ie. just the CSC matrix coefficients for one matrix, or just the 
> > entries for a single gamma ramp. Again ideally we should make the 
> > blobs hardware agnostic, but still allow precise control over the output data.
> >
> > I think this is going to involve first going over our hardware 
> > features, trying to find the common patterns between different 
> > generations. If there's a way to make something that works across 
> > the board for us, or at least across a wide range, then we should 
> > also ask for some input on dri-devel whether the proposed property 
> > would work for other people. We may need to define new property 
> > types to more precisely define what the value of the property actually means.
> >
> 
> Our hardware has similar features, so I'm sure there will be quite a 
> bit of common ground.  I also vote for properties.

Thirded. Tegra should be able to use a hardware-agnostic description of these as well. I wonder if perhaps VESA or some other standard already defines such a format for some of these properties.

Thierry