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Date: Tue, 19 Mar 2024 11:21:47 +0100
From: Maxime Ripard <mripard@kernel.org>
To: Ville =?utf-8?B?U3lyasOkbMOk?= <ville.syrjala@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
	Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@gmail.com>, 
	Daniel Vetter <daniel@ffwll.ch>, Jonathan Corbet <corbet@lwn.net>, 
	Sandy Huang <hjc@rock-chips.com>, Heiko =?utf-8?Q?St=C3=BCbner?= <heiko@sntech.de>, 
	Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@gmail.com>, 
	Samuel Holland <samuel@sholland.org>, Hans Verkuil <hverkuil@xs4all.nl>, 
	Sebastian Wick <sebastian.wick@redhat.com>, dri-devel@lists.freedesktop.org, 
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-sunxi@lists.linux.dev
Subject: Re: [PATCH v9 20/27] drm/connector: hdmi: Add Infoframes generation
Message-ID: <20240319-gabby-marigold-poodle-c5a27f@houat>
References: <20240311-kms-hdmi-connector-state-v9-0-d45890323344@kernel.org>
 <20240311-kms-hdmi-connector-state-v9-20-d45890323344@kernel.org>
 <ZfQFLR2xO6vUpAJ9@intel.com>
 <20240318-abstract-myna-of-exercise-adfcde@houat>
 <ZfhnsgYfwe_3mpWx@intel.com>
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On Mon, Mar 18, 2024 at 06:11:30PM +0200, Ville Syrj=E4l=E4 wrote:
> On Mon, Mar 18, 2024 at 02:49:47PM +0100, Maxime Ripard wrote:
> > Hi,
> >=20
> > On Fri, Mar 15, 2024 at 10:22:05AM +0200, Ville Syrj=E4l=E4 wrote:
> > > On Mon, Mar 11, 2024 at 03:49:48PM +0100, Maxime Ripard wrote:
> > > > Infoframes in KMS is usually handled by a bunch of low-level helpers
> > > > that require quite some boilerplate for drivers. This leads to
> > > > discrepancies with how drivers generate them, and which are actually
> > > > sent.
> > > >=20
> > > > Now that we have everything needed to generate them in the HDMI
> > > > connector state, we can generate them in our common logic so that
> > > > drivers can simply reuse what we precomputed.
> > > >=20
> > > > Signed-off-by: Maxime Ripard <mripard@kernel.org>
> > > > ---
> > > >  drivers/gpu/drm/Kconfig                            |   1 +
> > > >  drivers/gpu/drm/drm_atomic_state_helper.c          | 323 +++++++++=
++++++++++++
> > > >  drivers/gpu/drm/drm_connector.c                    |  14 +
> > > >  .../gpu/drm/tests/drm_atomic_state_helper_test.c   |   1 +
> > > >  drivers/gpu/drm/tests/drm_connector_test.c         |  12 +
> > > >  include/drm/drm_atomic_state_helper.h              |   8 +
> > > >  include/drm/drm_connector.h                        | 133 +++++++++
> > > >  7 files changed, 492 insertions(+)
> > > >=20
> > > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > > > index 872edb47bb53..ad9c467e20ce 100644
> > > > --- a/drivers/gpu/drm/Kconfig
> > > > +++ b/drivers/gpu/drm/Kconfig
> > > > @@ -97,10 +97,11 @@ config DRM_KUNIT_TEST
> > > >  	  If in doubt, say "N".
> > > > =20
> > > >  config DRM_KMS_HELPER
> > > >  	tristate
> > > >  	depends on DRM
> > > > +	select DRM_DISPLAY_HDMI_HELPER
> > > >  	help
> > > >  	  CRTC helpers for KMS drivers.
> > > > =20
> > > >  config DRM_DEBUG_DP_MST_TOPOLOGY_REFS
> > > >          bool "Enable refcount backtrace history in the DP MST help=
ers"
> > > > diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gp=
u/drm/drm_atomic_state_helper.c
> > > > index e66272c0d006..2bf53666fc9d 100644
> > > > --- a/drivers/gpu/drm/drm_atomic_state_helper.c
> > > > +++ b/drivers/gpu/drm/drm_atomic_state_helper.c
> > > > @@ -36,10 +36,12 @@
> > > >  #include <drm/drm_plane.h>
> > > >  #include <drm/drm_print.h>
> > > >  #include <drm/drm_vblank.h>
> > > >  #include <drm/drm_writeback.h>
> > > > =20
> > > > +#include <drm/display/drm_hdmi_helper.h>
> > > > +
> > > >  #include <linux/slab.h>
> > > >  #include <linux/dma-fence.h>
> > > > =20
> > > >  /**
> > > >   * DOC: atomic state reset and initialization
> > > > @@ -912,10 +914,143 @@ hdmi_compute_config(const struct drm_connect=
or *connector,
> > > >  	}
> > > > =20
> > > >  	return -EINVAL;
> > > >  }
> > > > =20
> > > > +static int hdmi_generate_avi_infoframe(const struct drm_connector =
*connector,
> > > > +				       struct drm_connector_state *state)
> > > > +{
> > > > +	const struct drm_display_mode *mode =3D
> > > > +		connector_state_get_mode(state);
> > > > +	struct drm_connector_hdmi_infoframe *infoframe =3D
> > > > +		&state->hdmi.infoframes.avi;
> > > > +	struct hdmi_avi_infoframe *frame =3D
> > > > +		&infoframe->data.avi;
> > > > +	bool is_full_range =3D state->hdmi.is_full_range;
> > > > +	enum hdmi_quantization_range rgb_quant_range =3D
> > > > +		is_full_range ? HDMI_QUANTIZATION_RANGE_FULL : HDMI_QUANTIZATION=
_RANGE_LIMITED;
> > > > +	int ret;
> > > > +
> > > > +	ret =3D drm_hdmi_avi_infoframe_from_display_mode(frame, connector=
, mode);
> > > > +	if (ret)
> > > > +		return ret;
> > > > +
> > > > +	frame->colorspace =3D state->hdmi.output_format;
> > > > +
> > > > +	drm_hdmi_avi_infoframe_quant_range(frame, connector, mode, rgb_qu=
ant_range);
> > >=20
> > > drm_hdmi_avi_infoframe_quant_range() doesn't handle YCbCr currently.
> >=20
> > I guess it's not really a problem anymore if we drop YUV422 selection,
> > but I'll add a comment.
> >=20
> > > > +	drm_hdmi_avi_infoframe_colorimetry(frame, state);
> > > > +	drm_hdmi_avi_infoframe_bars(frame, state);
> > > > +
> > > > +	infoframe->set =3D true;
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > <snip>
> > > > +
> > > > +#define UPDATE_INFOFRAME(c, os, ns, i)				\
> > > > +	write_or_clear_infoframe(c,				\
> > > > +				 &(c)->hdmi.infoframes.i,	\
> > > > +				 &(os)->hdmi.infoframes.i,	\
> > > > +				 &(ns)->hdmi.infoframes.i)
> > >=20
> > > This macro feels like pointless obfuscation to me.
> >=20
> > I'll remove it then.
> >=20
> > > <snip>
> > > > @@ -1984,20 +2063,73 @@ struct drm_connector {
> > > > =20
> > > >  	/**
> > > >  	 * @hdmi: HDMI-related variable and properties.
> > > >  	 */
> > > >  	struct {
> > > > +#define DRM_CONNECTOR_HDMI_VENDOR_LEN	8
> > > > +		/**
> > > > +		 * @vendor: HDMI Controller Vendor Name
> > > > +		 */
> > > > +		unsigned char vendor[DRM_CONNECTOR_HDMI_VENDOR_LEN] __nonstring;
> > > > +
> > > > +#define DRM_CONNECTOR_HDMI_PRODUCT_LEN	16
> > > > +		/**
> > > > +		 * @product: HDMI Controller Product Name
> > > > +		 */
> > > > +		unsigned char product[DRM_CONNECTOR_HDMI_PRODUCT_LEN] __nonstrin=
g;
> > > > +
> > > >  		/**
> > > >  		 * @supported_formats: Bitmask of @hdmi_colorspace
> > > >  		 * supported by the controller.
> > > >  		 */
> > > >  		unsigned long supported_formats;
> > > > =20
> > > >  		/**
> > > >  		 * @funcs: HDMI connector Control Functions
> > > >  		 */
> > > >  		const struct drm_connector_hdmi_funcs *funcs;
> > > > +
> > > > +		/**
> > > > +		 * @infoframes: Current Infoframes output by the connector
> > > > +		 */
> > > > +		struct {
> > > > +			/**
> > > > +			 * @lock: Mutex protecting against concurrent access to
> > > > +			 * the infoframes, most notably between KMS and ALSA.
> > > > +			 */
> > > > +			struct mutex lock;
> > > > +
> > > > +			/**
> > > > +			 * @audio: Current Audio Infoframes structure. Protected
> > > > +			 * by @lock.
> > > > +			 */
> > > > +			struct drm_connector_hdmi_infoframe audio;
> > > > +
> > > > +			/**
> > > > +			 * @avi: Current AVI Infoframes structure. Protected by
> > > > +			 * @lock.
> > > > +			 */
> > > > +			struct drm_connector_hdmi_infoframe avi;
> > > > +
> > > > +			/**
> > > > +			 * @hdr_drm: Current DRM (Dynamic Range and Mastering)
> > > > +			 * Infoframes structure. Protected by @lock.
> > > > +			 */
> > > > +			struct drm_connector_hdmi_infoframe hdr_drm;
> > > > +
> > > > +			/**
> > > > +			 * @spd: Current SPD Infoframes structure. Protected by
> > > > +			 * @lock.
> > > > +			 */
> > > > +			struct drm_connector_hdmi_infoframe spd;
> > > > +
> > > > +			/**
> > > > +			 * @vendor: Current HDMI Vendor Infoframes structure.
> > > > +			 * Protected by @lock.
> > > > +			 */
> > > > +			struct drm_connector_hdmi_infoframe hdmi;
> > > > +		} infoframes;
> > > >  	} hdmi;
> > >=20
> > > What's the deal with this bloat? These are already tracked in the
> > > connector's state so this looks entirely redundant.
> >=20
> > The next patch in this series is about adding debugfs entries to read
> > the infoframes, and thus we need to care about concurrency between
> > debugfs files accesses and commits. Copying the things we care about
> > from the state to the entity is the typical solution for that, but I
> > guess we could also take the proper locks and access the current
> > connector state.
>=20
> Yeah, just lock and dump the latest state. That is the only thing
> that should of interest to anyone in userspace.
>=20
> Also are you actually adding some kind of ad-hoc state dump things
> just for these? Why not do whatever is needed to include them in
> the normal .atomic_state_print() stuff?

Yeah, part of the reason for the whole thing is so we can make
edid-decode check the sanity of generated infoframes, for both v4l2 and
DRM. Hans has been working on it and has a prototype based on this work.

But you're right, we should probably add them to atomic_state_print too

Maxime

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