Re: [Intel-gfx] [RFC v4 3/8] drm: Add Plane CTM property

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Aug 22, 2018 at 12:11:42PM +0100, Brian Starkey wrote:
> Hi,
> 
> On Wed, Aug 22, 2018 at 12:53:58PM +0300, Ville Syrjälä wrote:
> >On Wed, Aug 22, 2018 at 08:40:19AM +0000, Lankhorst, Maarten wrote:
> >> fre 2018-08-17 klockan 19:48 +0530 skrev Uma Shankar:
> >> > Add a blob property for plane CSC usage.
> >> >
> >> > v2: Rebase
> >> >
> >> > v3: Fixed Sean, Paul's review comments. Moved the property from
> >> > mode_config to drm_plane. Created a helper function to instantiate
> >> > these properties and removed from drm_mode_create_standard_properties
> >> > Added property documentation as suggested by Daniel, Vetter.
> >> >
> >> > v4: Rebase
> >> >
> >> > Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> >> > ---
> >> >  Documentation/gpu/drm-kms.rst       |  3 +++
> >> >  drivers/gpu/drm/drm_atomic.c        | 10 ++++++++++
> >> >  drivers/gpu/drm/drm_atomic_helper.c |  4 ++++
> >> >  drivers/gpu/drm/drm_plane.c         | 12 ++++++++++++
> >> >  include/drm/drm_plane.h             | 15 +++++++++++++++
> >> >  5 files changed, 44 insertions(+)
> >> >
> >> > diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-
> >> > kms.rst
> >> > index 8b10b12..16d6d8d 100644
> >> > --- a/Documentation/gpu/drm-kms.rst
> >> > +++ b/Documentation/gpu/drm-kms.rst
> >> > @@ -560,6 +560,9 @@ Plane Color Management Properties
> >> >  .. kernel-doc:: drivers/gpu/drm/drm_plane.c
> >> >     :doc: degamma_lut_size_property
> >> >
> >> > +.. kernel-doc:: drivers/gpu/drm/drm_plane.c
> >> > +   :doc: ctm_property
> >> > +
> >> >  Tile Group Property
> >> >  -------------------
> >> >
> >> > diff --git a/drivers/gpu/drm/drm_atomic.c
> >> > b/drivers/gpu/drm/drm_atomic.c
> >> > index f8cad9b..ddda935 100644
> >> > --- a/drivers/gpu/drm/drm_atomic.c
> >> > +++ b/drivers/gpu/drm/drm_atomic.c
> >> > @@ -917,6 +917,14 @@ static int drm_atomic_plane_set_property(struct
> >> > drm_plane *plane,
> >> >  					&replaced);
> >> >  		state->color_mgmt_changed |= replaced;
> >> >  		return ret;
> >> > +	} else if (property == plane->ctm_property) {
> >> > +		ret = drm_atomic_replace_property_blob_from_id(dev,
> >> > +					&state->ctm,
> >> > +					val,
> >> > +					sizeof(struct
> >> > drm_color_ctm), -1,
> >> > +					&replaced);
> >> > +		state->color_mgmt_changed |= replaced;
> >> > +		return ret;
> >> >  	} else if (plane->funcs->atomic_set_property) {
> >> >  		return plane->funcs->atomic_set_property(plane,
> >> > state,
> >> >  				property, val);
> >> > @@ -988,6 +996,8 @@ static int drm_atomic_plane_set_property(struct
> >> > drm_plane *plane,
> >> >  	} else if (property == plane->degamma_lut_property) {
> >> >  		*val = (state->degamma_lut) ?
> >> >  			state->degamma_lut->base.id : 0;
> >> > +	} else if (property == plane->ctm_property) {
> >> > +		*val = (state->ctm) ? state->ctm->base.id : 0;
> >> >  	} else if (plane->funcs->atomic_get_property) {
> >> >  		return plane->funcs->atomic_get_property(plane,
> >> > state, property, val);
> >> >  	} else {
> >> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> >> > b/drivers/gpu/drm/drm_atomic_helper.c
> >> > index 67c5b51..866181f 100644
> >> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> >> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> >> > @@ -3616,6 +3616,9 @@ void
> >> > __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
> >> >
> >> >  	if (state->degamma_lut)
> >> >  		drm_property_blob_get(state->degamma_lut);
> >> > +	if (state->ctm)
> >> > +		drm_property_blob_get(state->ctm);
> >> > +
> >> >  	state->color_mgmt_changed = false;
> >> >  }
> >> >  EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);
> >> > @@ -3663,6 +3666,7 @@ void
> >> > __drm_atomic_helper_plane_destroy_state(struct drm_plane_state
> >> > *state)
> >> >  		drm_crtc_commit_put(state->commit);
> >> >
> >> >  	drm_property_blob_put(state->degamma_lut);
> >> > +	drm_property_blob_put(state->ctm);
> >> >  }
> >> >  EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
> >> >
> >> > diff --git a/drivers/gpu/drm/drm_plane.c
> >> > b/drivers/gpu/drm/drm_plane.c
> >> > index 03e0560..97520b1 100644
> >> > --- a/drivers/gpu/drm/drm_plane.c
> >> > +++ b/drivers/gpu/drm/drm_plane.c
> >> > @@ -489,6 +489,11 @@ int drm_mode_plane_set_obj_prop(struct drm_plane
> >> > *plane,
> >> >   *
> >> >   * degamma_lut_size_property:
> >> >   *	Range Property to indicate size of the plane degamma LUT.
> >> > + *
> >> > + * ctm_property:
> >> > + *	Blob property which allows a userspace to provide CTM
> >> > coefficients
> >> > + *	to do color space conversion or any other enhancement by
> >> > doing a
> >> > + *	matrix multiplication using the h/w CTM processing engine
> >> >   */
> >> >  int drm_plane_color_create_prop(struct drm_device *dev,
> >> >  				struct drm_plane *plane)
> >> > @@ -509,6 +514,13 @@ int drm_plane_color_create_prop(struct
> >> > drm_device *dev,
> >> >  		return -ENOMEM;
> >> >  	plane->degamma_lut_size_property = prop;
> >> >
> >> > +	prop = drm_property_create(dev,
> >> > +			DRM_MODE_PROP_BLOB,
> >> > +			"PLANE_CTM", 0);
> >> > +	if (!prop)
> >> > +		return -ENOMEM;
> >> > +	plane->ctm_property = prop;
> >> > +
> >> >  	return 0;
> >> >  }
> >> >  EXPORT_SYMBOL(drm_plane_color_create_prop);
> >> > diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> >> > index 28357ac..5143277 100644
> >> > --- a/include/drm/drm_plane.h
> >> > +++ b/include/drm/drm_plane.h
> >> > @@ -183,6 +183,14 @@ struct drm_plane_state {
> >> >  	struct drm_property_blob *degamma_lut;
> >> >
> >> >  	/**
> >> > +	 * @ctm:
> >> > +	 *
> >> > +	 * Color transformation matrix. See
> >> > drm_plane_enable_color_mgmt(). The
> >> > +	 * blob (if not NULL) is a &struct drm_color_ctm.
> >> > +	 */
> >> > +	struct drm_property_blob *ctm;
> >> > +
> >> > +	/**
> >> >  	 * @commit: Tracks the pending commit to prevent use-after-
> >> > free conditions,
> >> >  	 * and for async plane updates.
> >> >  	 *
> >> > @@ -698,6 +706,13 @@ struct drm_plane {
> >> >  	 * size of the degamma LUT as supported by the driver (read-
> >> > only).
> >> >  	 */
> >> >  	struct drm_property *degamma_lut_size_property;
> >> > +
> >> > +	/**
> >> > +	 * @plane_ctm_property: Optional Plane property to set the
> >> > +	 * matrix used to convert colors after the lookup in the
> >> > +	 * degamma LUT.
> >> > +	 */
> >> > +	struct drm_property *ctm_property;
> >> >
> >> I'm assuming degamma is done before converting with CTM.
> >>
> >> But how does this interact with YUV formats? I'm not sure this is
> >> explicitly defined. I'm assuming R->Cr G -> Y, B = Cb for degamma
> >> tables.
> >
> >The pipeline is (or at least should be IMO):
> >ycbcr->rgb -> degamma -> ctm -> gamma
> >
> 
> That's what I'm expecting too.
> 
> >We should document the full pipeline (including the crtc portions) in
> >some docs.
> 
> I fully agree with Ville here, we've been around this loop a few
> times, so the full pipeline and expectations need to be captured
> in docs (IMO before the properties can be decided).
> 
> It's slightly unfortunate that the merged ycbcr->rgb properties only
> describe the format of the incoming buffer, without any specification
> of what the driver is meant to do with that information (what
> conversion is meant to be performed?).

So far the idea has been that the internal pipeline is assumed to be
full range RGB. If/when someone needs something else they can try to
design a new API for it. If we had tried to deal with ycbcr passthrough
and whatnot when adding the encoding/range props we probably still
wouldn't have landed anything.

But yeah, the docs should of course explicitly state this fact.

-- 
Ville Syrjälä
Intel
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