Re: [v2 0/7] Add Multi Segment Gamma Support

["Shankar, Uma" <uma.shankar@intel.com>]

>-----Original Message-----
>From: dri-devel [mailto:dri-devel-bounces@lists.freedesktop.org] On Behalf Of Ville
>Syrjälä
>Sent: Monday, April 8, 2019 9:15 PM
>To: Shankar, Uma <uma.shankar@intel.com>
>Cc: dcastagna@chromium.org; intel-gfx@lists.freedesktop.org; dri-
>devel@lists.freedesktop.org; seanpaul@chromium.org; Syrjala, Ville
><ville.syrjala@intel.com>; Lankhorst, Maarten <maarten.lankhorst@intel.com>
>Subject: Re: [Intel-gfx] [v2 0/7] Add Multi Segment Gamma Support
>
>On Mon, Apr 08, 2019 at 03:40:39PM +0000, Shankar, Uma wrote:
>>
>>
>> >-----Original Message-----
>> >From: Ville Syrjälä [mailto:ville.syrjala@linux.intel.com]
>> >Sent: Monday, April 8, 2019 8:27 PM
>> >To: Shankar, Uma <uma.shankar@intel.com>
>> >Cc: dcastagna@chromium.org; intel-gfx@lists.freedesktop.org; dri-
>> >devel@lists.freedesktop.org; seanpaul@chromium.org; Syrjala, Ville
>> ><ville.syrjala@intel.com>; Lankhorst, Maarten
>> ><maarten.lankhorst@intel.com>
>> >Subject: Re: [Intel-gfx] [v2 0/7] Add Multi Segment Gamma Support
>> >
>> >On Mon, Apr 08, 2019 at 02:40:51PM +0000, Shankar, Uma wrote:
>> >>
>> >>
>> >> >-----Original Message-----
>> >> >From: Ville Syrjälä [mailto:ville.syrjala@linux.intel.com]
>> >> >Sent: Monday, April 8, 2019 6:01 PM
>> >> >To: Shankar, Uma <uma.shankar@intel.com>
>> >> >Cc: dcastagna@chromium.org; intel-gfx@lists.freedesktop.org; dri-
>> >> >devel@lists.freedesktop.org; seanpaul@chromium.org; Syrjala, Ville
>> >> ><ville.syrjala@intel.com>; Lankhorst, Maarten
>> >> ><maarten.lankhorst@intel.com>
>> >> >Subject: Re: [Intel-gfx] [v2 0/7] Add Multi Segment Gamma Support
>> >> >
>> >> >On Mon, Apr 08, 2019 at 12:26:23PM +0000, Shankar, Uma wrote:
>> >> >>
>> >> >>
>> >> >> >-----Original Message-----
>> >> >> >From: dri-devel
>> >> >> >[mailto:dri-devel-bounces@lists.freedesktop.org]
>> >> >> >On Behalf Of Ville Syrjälä
>> >> >> >Sent: Friday, April 5, 2019 9:42 PM
>> >> >> >To: Shankar, Uma <uma.shankar@intel.com>
>> >> >> >Cc: dcastagna@chromium.org; intel-gfx@lists.freedesktop.org;
>> >> >> >dri- devel@lists.freedesktop.org; seanpaul@chromium.org;
>> >> >> >Syrjala, Ville <ville.syrjala@intel.com>; Lankhorst, Maarten
>> >> >> ><maarten.lankhorst@intel.com>
>> >> >> >Subject: Re: [Intel-gfx] [v2 0/7] Add Multi Segment Gamma
>> >> >> >Support
>> >> >> >
>> >> >> >On Mon, Apr 01, 2019 at 11:00:04PM +0530, Uma Shankar wrote:
>> >> >> >> This series adds support for programmable gamma modes and
>> >> >> >> exposes a property interface for the same. Also added,
>> >> >> >> support for multi segment gamma mode introduced in ICL+
>> >> >> >>
>> >> >> >> It creates 2 property interfaces :
>> >> >> >> 1. GAMMA_MODE_CAPS: This is immutable property and exposes
>> >> >> >> the various gamma modes supported and the lut ranges. This is
>> >> >> >> an enum property with element as blob id. Getting the blob id
>> >> >> >> in userspace, user can get the mode supported and also the
>> >> >> >> range of gamma mode supported with number of lut coefficients.
>> >> >> >>
>> >> >> >> 2. GAMMA_MODE: This is for user to set the gamma mode and
>> >> >> >> send the lut values for that particular mode.
>> >> >> >
>> >> >> >I think we should just go for the BLOB_ENUM prop type instead.
>> >> >> >Then the possible values and the current value are all part of the same prop.
>> >> >>
>> >> >> Hi Ville,
>> >> >> With the current approach, we have enum property with values as
>> >> >> blob_ids (representing platform capabilities). This should not
>> >> >> get modified and needs to be immutable.
>> >> >
>> >> >That's not quite what we want. We want to let the user modify the
>> >> >current value so that they can actually select the gamma mode.
>> >> >Otherwise we need yet another prop for it, or we have to deduce it
>> >> >from the LUT size (that apporach would actually work for i915 but
>> >> >may not work for other drivers/hardware).
>> >> >
>> >> >>
>> >> >> Userspace can query the property and get the blob using the blob_ids.
>> >> >> Thereby getting all the platform capabilities.
>> >> >>
>> >> >> Now to set the LUT values, he can use another blob property and
>> >> >> pass the luts.  This is inline to how gamma/degamma is
>> >> >> implemented where we have one immutable LUT_SIZE property
>> >> >> (indicating number of
>> >> >> luts) and another blob property for actual lut values..
>> >>
>> >> Hi Ville,
>> >> Just to clarify and clear some doubts :)
>> >>
>> >> We should be able to set the gamma mode using the blob enum value.
>> >> Userspace will get the list enum vals (blob ids with mode name
>> >> embedded) and
>> >select one and do a setprop to set a mode.
>> >> Driver will get the blob_id and will be able to get the mode to be
>> >> set.  So exposing capabilities and setting the mode should be
>> >> possible with this one
>> >property. I hope my understanding is correct.
>> >>
>> >> Now to send the actual blob values to be set, we need to use some
>> >> other property interface. Should we use the currently available
>> >> "gamma blob
>> >(gamma_lut_property)" property to send the lut values.
>> >> The challenge there is that it currently uses 16 bit lut values
>> >> struct drm_color_lut {
>> >>         __u16 red;
>> >>         __u16 green;
>> >>         __u16 blue;
>> >>         __u16 reserved;
>> >> };
>> >> which is not sufficient for HDR usecases. Or should we need a new
>> >> property for
>> >advance lut/extended lut like below:
>> >> https://patchwork.freedesktop.org/patch/294732/?series=30875&rev=7
>> >>
>> >> What do you suggest ?
>> >
>> >I was thinking that we might get away with reusing the current props
>> >and just change the interpretation of the data when gamma_mode is
>> >set. But I'm not sure that's going to work out so well if one client
>> >sets this up and then another client comes along that doesn't
>> >understand the new props at all. But even with separate props I think
>> >we might still end up in a mess because the new client wouldn't know
>> >how to unset the higher precision LUT before setting up the old style prop and the
>kernel would then refuse the operation with with both props being set.
>> >
>> >So I think we might need a client cap for this which simply changes
>> >how the data in the existing props is represented. So internally we
>> >could always store things in the new high precision format, but we'd
>> >convert to/from the old format when dealing with an older client.
>>
>> We could also say that if a legacy gamma_mode_property is set (which
>> will be used by legacy apps or apps not aware of new interface), in
>> driver we will simply unset the earlier gamma_mode and fallback to
>> legacy mode (whatever it was for a particular platform). This way we
>> should be able to deal with this situation and an explicit unset may not be needed.
>What do you think ?
>
>I don't want (non-immutable) properties that magically change values.
>That way lies madness.

Oh ok. So do you suggest that we add some kind of  flag to be set by user, based on
which we take either legacy or advance_gamma path. Is my understanding correct ?

>>
>> >>
>> >> Note: I have currently used 16bit values only to get the feedback on the
>approach.
>> >>
>> >> Regards,
>> >> Uma Shankar
>> >>
>> >> >>
>> >> >> >>
>> >> >> >> v2: Used Ville's design and approach to define the interfaces.
>> >> >> >> Addressed Matt Roper's review feedback and re-ordered the patches.
>> >> >> >>
>> >> >> >> Uma Shankar (5):
>> >> >> >>   drm: Add gamma mode property
>> >> >> >>   drm/i915/icl: Add register definitions for Multi Segmented gamma
>> >> >> >>   drm/i915/icl: Add support for multi segmented gamma mode
>> >> >> >>   drm/i915: Add gamma mode caps property
>> >> >> >>   drm/i915: Attach gamma mode property
>> >> >> >>
>> >> >> >> Ville Syrjälä (2):
>> >> >> >>   drm: Add gamma mode caps property
>> >> >> >>   drm/i915: Define color lut range structure
>> >> >> >>
>> >> >> >>  drivers/gpu/drm/drm_atomic_uapi.c    |  13 +
>> >> >> >>  drivers/gpu/drm/drm_color_mgmt.c     | 110 +++++++++
>> >> >> >>  drivers/gpu/drm/i915/i915_reg.h      |  17 ++
>> >> >> >>  drivers/gpu/drm/i915/intel_color.c   | 465
>> >> >> >++++++++++++++++++++++++++++++++++-
>> >> >> >>  drivers/gpu/drm/i915/intel_display.c |   5 +
>> >> >> >>  include/drm/drm_color_mgmt.h         |  11 +
>> >> >> >>  include/drm/drm_crtc.h               |  17 ++
>> >> >> >>  include/drm/drm_mode_config.h        |  10 +
>> >> >> >>  include/uapi/drm/drm_mode.h          |  49 ++++
>> >> >> >>  9 files changed, 690 insertions(+), 7 deletions(-)
>> >> >> >>
>> >> >> >> --
>> >> >> >> 1.9.1
>> >> >> >>
>> >> >> >> _______________________________________________
>> >> >> >> Intel-gfx mailing list
>> >> >> >> Intel-gfx@lists.freedesktop.org
>> >> >> >> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> >> >> >
>> >> >> >--
>> >> >> >Ville Syrjälä
>> >> >> >Intel
>> >> >> >_______________________________________________
>> >> >> >dri-devel mailing list
>> >> >> >dri-devel@lists.freedesktop.org
>> >> >> >https://lists.freedesktop.org/mailman/listinfo/dri-devel
>> >> >
>> >> >--
>> >> >Ville Syrjälä
>> >> >Intel
>> >
>> >--
>> >Ville Syrjälä
>> >Intel
>
>--
>Ville Syrjälä
>Intel
>_______________________________________________
>dri-devel mailing list
>dri-devel@lists.freedesktop.org
>https://lists.freedesktop.org/mailman/listinfo/dri-devel
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx