Re: [PATCH v7 1/2] drm: content-type property for HDMI connector

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, May 02, 2018 at 08:09:24AM +0000, Lisovskiy, Stanislav wrote:
> On Mon, 2018-04-30 at 17:00 +0200, Daniel Vetter wrote:
> > On Fri, Apr 27, 2018 at 10:40:00PM +0300, Ville Syrjälä wrote:
> > > On Mon, Apr 23, 2018 at 10:34:41AM +0300, StanLis wrote:
> > > > From: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> > > > 
> > > > Added content_type property to drm_connector_state
> > > > in order to properly handle external HDMI TV content-type
> > > > setting.
> > > > 
> > > > v2:
> > > >  * Moved helper function which attaches content type property
> > > >    to the drm core, as was suggested.
> > > >    Removed redundant connector state initialization.
> > > > 
> > > > v3:
> > > >  * Removed caps in drm_content_type_enum_list.
> > > >    After some discussion it turned out that HDMI Spec 1.4
> > > >    was wrongly assuming that IT Content(itc) bit doesn't affect
> > > >    Content type states, however itc bit needs to be manupulated
> > > >    as well. In order to not expose additional property for itc,
> > > >    for sake of simplicity it was decided to bind those together
> > > >    in same "content type" property.
> > > > 
> > > > v4:
> > > >  * Added it_content checking in
> > > > intel_digital_connector_atomic_check.
> > > >    Fixed documentation for new content type enum.
> > > > 
> > > > v5:
> > > >  * Moved patch revision's description to commit messages.
> > > > 
> > > > v6:
> > > >  * Minor naming fix for the content type enumeration string.
> > > > 
> > > > v7:
> > > >  * Fix parameter name for documentation and parameter alignment
> > > >    in order not to get warning. Added Content Type description to
> > > >    new HDMI connector properties section.
> > > > 
> > > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com
> > > > >
> > > > ---
> > > >  Documentation/gpu/drm-kms.rst        |  6 +++
> > > >  Documentation/gpu/kms-properties.csv |  1 +
> > > >  drivers/gpu/drm/drm_atomic.c         | 17 +++++++
> > > >  drivers/gpu/drm/drm_connector.c      | 74
> > > > ++++++++++++++++++++++++++++
> > > >  drivers/gpu/drm/drm_edid.c           |  2 +
> > > >  include/drm/drm_connector.h          | 18 +++++++
> > > >  include/drm/drm_mode_config.h        |  5 ++
> > > >  include/uapi/drm/drm_mode.h          |  7 +++
> > > >  8 files changed, 130 insertions(+)
> > > > 
> > > > diff --git a/Documentation/gpu/drm-kms.rst
> > > > b/Documentation/gpu/drm-kms.rst
> > > > index 1dffd1ac4cd4..e233c2626bd0 100644
> > > > --- a/Documentation/gpu/drm-kms.rst
> > > > +++ b/Documentation/gpu/drm-kms.rst
> > > > @@ -517,6 +517,12 @@ Standard Connector Properties
> > > >  .. kernel-doc:: drivers/gpu/drm/drm_connector.c
> > > >     :doc: standard connector properties
> > > >  
> > > > +HDMI Specific Connector Properties
> > > > +-----------------------------
> > > > +
> > > > +.. kernel-doc:: drivers/gpu/drm/drm_connector.c
> > > > +   :doc: HDMI connector properties
> > > > +
> > > >  Plane Composition Properties
> > > >  ----------------------------
> > > >  
> > > > diff --git a/Documentation/gpu/kms-properties.csv
> > > > b/Documentation/gpu/kms-properties.csv
> > > > index 6b28b014cb7d..3567c986bd7d 100644
> > > > --- a/Documentation/gpu/kms-properties.csv
> > > > +++ b/Documentation/gpu/kms-properties.csv
> > > > @@ -17,6 +17,7 @@ Owner Module/Drivers,Group,Property
> > > > Name,Type,Property Values,Object attached,De
> > > >  ,Virtual GPU,“suggested X”,RANGE,"Min=0,
> > > > Max=0xffffffff",Connector,property to suggest an X offset for a
> > > > connector
> > > >  ,,“suggested Y”,RANGE,"Min=0, Max=0xffffffff",Connector,property
> > > > to suggest an Y offset for a connector
> > > >  ,Optional,"""aspect ratio""",ENUM,"{ ""None"", ""4:3"", ""16:9""
> > > > }",Connector,TDB
> > > > +,Optional,"""content type""",ENUM,"{ ""No Data"", ""Graphics"",
> > > > ""Photo"", ""Cinema"", ""Game"" }",Connector,TBD
> > > >  i915,Generic,"""Broadcast RGB""",ENUM,"{ ""Automatic"",
> > > > ""Full"", ""Limited 16:235"" }",Connector,"When this property is
> > > > set to Limited 16:235 and CTM is set, the hardware will be
> > > > programmed with the result of the multiplication of CTM by the
> > > > limited range matrix to ensure the pixels normaly in the range
> > > > 0..1.0 are remapped to the range 16/255..235/255."
> > > >  ,,“audio”,ENUM,"{ ""force-dvi"", ""off"", ""auto"", ""on""
> > > > }",Connector,TBD
> > > >  ,SDVO-TV,“mode”,ENUM,"{ ""NTSC_M"", ""NTSC_J"", ""NTSC_443"",
> > > > ""PAL_B"" } etc.",Connector,TBD
> > > > diff --git a/drivers/gpu/drm/drm_atomic.c
> > > > b/drivers/gpu/drm/drm_atomic.c
> > > > index 7d25c42f22db..479499f5848e 100644
> > > > --- a/drivers/gpu/drm/drm_atomic.c
> > > > +++ b/drivers/gpu/drm/drm_atomic.c
> > > > @@ -1266,6 +1266,15 @@ static int
> > > > drm_atomic_connector_set_property(struct drm_connector
> > > > *connector,
> > > >  			state->link_status = val;
> > > >  	} else if (property == config->aspect_ratio_property) {
> > > >  		state->picture_aspect_ratio = val;
> > > > +	} else if (property == config->content_type_property) {
> > > > +		/*
> > > > +		 * Lowest two bits of content_type property
> > > > control
> > > > +		 * content_type, bit 2 controls itc bit.
> > > > +		 * It was decided to have a single property
> > > > called
> > > > +		 * content_type, instead of content_type and
> > > > itc.
> > > > +		 */
> > > > +		state->content_type = val & 3;
> > > > +		state->it_content = val >> 2;
> > > >  	} else if (property == connector->scaling_mode_property) 
> > > > {
> > > >  		state->scaling_mode = val;
> > > >  	} else if (property == connector-
> > > > >content_protection_property) {
> > > > @@ -1351,6 +1360,14 @@ drm_atomic_connector_get_property(struct
> > > > drm_connector *connector,
> > > >  		*val = state->link_status;
> > > >  	} else if (property == config->aspect_ratio_property) {
> > > >  		*val = state->picture_aspect_ratio;
> > > > +	} else if (property == config->content_type_property) {
> > > > +		/*
> > > > +		 * Lowest two bits of content_type property
> > > > control
> > > > +		 * content_type, bit 2 controls itc bit.
> > > > +		 * It was decided to have a single property
> > > > called
> > > > +		 * content_type, instead of content_type and
> > > > itc.
> > > > +		 */
> > > > +		*val = state->content_type | (state->it_content
> > > > << 2);
> > > >  	} else if (property == connector->scaling_mode_property) 
> > > > {
> > > >  		*val = state->scaling_mode;
> > > >  	} else if (property == connector-
> > > > >content_protection_property) {
> > > > diff --git a/drivers/gpu/drm/drm_connector.c
> > > > b/drivers/gpu/drm/drm_connector.c
> > > > index b3cde897cd80..4f89602ebaf0 100644
> > > > --- a/drivers/gpu/drm/drm_connector.c
> > > > +++ b/drivers/gpu/drm/drm_connector.c
> > > > @@ -720,6 +720,14 @@ static const struct drm_prop_enum_list
> > > > drm_aspect_ratio_enum_list[] = {
> > > >  	{ DRM_MODE_PICTURE_ASPECT_16_9, "16:9" },
> > > >  };
> > > >  
> > > > +static const struct drm_prop_enum_list
> > > > drm_content_type_enum_list[] = {
> > > > +	{ DRM_MODE_CONTENT_TYPE_NO_DATA, "No Data" },
> > > > +	{ DRM_MODE_CONTENT_TYPE_GRAPHICS, "Graphics" },
> > > > +	{ DRM_MODE_CONTENT_TYPE_PHOTO, "Photo" },
> > > > +	{ DRM_MODE_CONTENT_TYPE_CINEMA, "Cinema" },
> > > > +	{ DRM_MODE_CONTENT_TYPE_GAME, "Game" },
> > > > +};
> > > > +
> > > >  static const struct drm_prop_enum_list
> > > > drm_panel_orientation_enum_list[] = {
> > > >  	{ DRM_MODE_PANEL_ORIENTATION_NORMAL,	"Normal"	
> > > > },
> > > >  	{ DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP,	"Upside
> > > > Down"	},
> > > > @@ -996,6 +1004,45 @@ int drm_mode_create_dvi_i_properties(struct
> > > > drm_device *dev)
> > > >  }
> > > >  EXPORT_SYMBOL(drm_mode_create_dvi_i_properties);
> > > >  
> > > > +
> > > > +/**
> > > > + * DOC: HDMI connector properties
> > > > + *
> > > > + * content type (HDMI specific):
> > > > + *	Indicates content type setting to be used in HDMI
> > > > infoframes to indicate
> > > > + *	content type for the external device, so that it
> > > > adjusts it's display
> > > > + *	settings accordingly.
> > > > + *
> > > > + *	The value of this property can be one of the
> > > > following:
> > > > + *
> > > > + *	- DRM_MODE_CONTENT_TYPE_NO_DATA = 0
> > > > + *		Content type is unknown, it content(itc) bit
> > > > is cleared.
> > > > + *	- DRM_MODE_CONTENT_TYPE_GRAPHICS = 4
> > > > + *		Content type is graphics, it content(itc) bit
> > > > is set.
> > > > + *	- DRM_MODE_CONTENT_TYPE_PHOTO = 5
> > > > + *		Content type is photo, itc bit is set.
> > > > + *	- DRM_MODE_CONTENT_TYPE_CINEMA = 6
> > > > + *		Content type is cinema, itc bit is set.
> > > > + *	- DRM_MODE_CONTENT_TYPE_GAME = 7
> > > > + *		Content type is game, itc bit is set.
> > > 
> > > I wonder if we're trying to document the uabi or the internals
> > > here.
> > > If we are interested in the uabi, then we should document the enum
> > > value strings here. If on the other hand we're trying to document
> > > the
> > > internal details then we should keep the DRM_CONTENT_TYPE_* stuff.
> > > Maybe we want both? The raw numbers I think we should just throw
> > > out.
> > > While they do have some specific meaning in the case (matching the
> > > bits
> > > in the infoframe), I'm not sure that's important enough to include
> > > in
> > > the docs. We could add a comment next to the
> > > DRM_MODE_CONTENT_TYPE_*
> > > definitions.
> > > 
> > > Looks like the content protection prop is documenting the internals
> > > only
> > > as well. Hmm. Actually it looks like those things are defined in
> > > the uapi
> > > header. Oh and the scaling mode prop also does that. This is all
> > > setting
> > > a rather bad example for userspace. Or maybe we've given up on the
> > > "the
> > > string is the uabi" notion entirely?
> > 
> > Wrt documenting uapi: That should imo also be in there, but I realize
> > it
> > makes it a bit a mess. The kerneldoc should definitely align with
> > other
> > property docs to make sure it all looks consistent (i.e. enumeration
> > list
> > with the same indentation as all the other properties).
> > 
> > I guess it'd be good if we can aim for "the string is the uabi", but
> > in
> > practice people will hardcode. For cases where this is likely I think
> > having the defines in the uapi header is probably better.
> > -Daniel
> 
> So how should we proceed then? In fact those
> definitions(DRM_MODE_CONTENT_TYPE_*) are already in 
> the uapi header(I've added them in the first patch), done
> same way as aspect ratio:
> 
> * Picture aspect ratio options */
> #define DRM_MODE_PICTURE_ASPECT_NONE            0
> #define DRM_MODE_PICTURE_ASPECT_4_3             1
> #define DRM_MODE_PICTURE_ASPECT_16_9            2

This aren't for a property, but for flags in the drm_mode_modeinfo
structure. That means it's required to have them as #defines.
> 
> /* HDMI content type and itc bit bound together for simplicity */
> #define DRM_MODE_CONTENT_TYPE_NO_DATA           0
> #define DRM_MODE_CONTENT_TYPE_GRAPHICS          4
> #define DRM_MODE_CONTENT_TYPE_PHOTO             5
> #define DRM_MODE_CONTENT_TYPE_CINEMA            6
> #define DRM_MODE_CONTENT_TYPE_GAME              7

These hare are for properties, which means they're not really required
since we have a getproperties ioctl to figure them out from the string.

> Should I just throw out numbers from kernel doc for drm_connector.c? Or
> may be add the enum string values? The thing is that other properties
> documentation seems to be done in different manner, for example
> "content protection" documents the defined enum values, while "scaling
> mode" documents the strings themself.

Yeah that's what Ville pointed out, we already screwed up a bit with the
content protection prop. For props, the string should be the uapi (but
we'll probably have to deal with userspace hardcoding stuff in some cases
no matter what).

> So I would be happy to implement it correctly, however just need some
> clue or hint here :)

I hope the above helps in clarifying things - aspect ratio ain't a
property.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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