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From: John Cox <jc@kynesim.co.uk>
To: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Cc: ezequiel@collabora.com, p.zabel@pengutronix.de,
	mchehab@kernel.org, robh+dt@kernel.org, shawnguo@kernel.org,
	s.hauer@pengutronix.de, festevam@gmail.com, lee.jones@linaro.org,
	gregkh@linuxfoundation.org, mripard@kernel.org,
	paul.kocialkowski@bootlin.com, wens@csie.org,
	jernej.skrabec@siol.net, hverkuil-cisco@xs4all.nl,
	emil.l.velikov@gmail.com, kernel@pengutronix.de,
	linux-imx@nxp.com, linux-media@vger.kernel.org,
	linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org,
	kernel@collabora.com, cphealy@gmail.com,
	Benjamin Gaignard <benjamin.gaignard@collabora.com>
Subject: Re: [PATCH v10 6/9] media: uapi: Add a control for HANTRO driver
Date: Wed, 05 May 2021 16:18:06 +0100
Message-ID: <6bd59glrp4fq3j3ngmbl5p4u7aethvrv34@4ax.com> (raw)
In-Reply-To: <20210420121046.181889-7-benjamin.gaignard@collabora.com>

>The HEVC HANTRO driver needs to know the number of bits to skip at
>the beginning of the slice header.
>That is a hardware specific requirement so create a dedicated control
>for this purpose.
>
>Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>---
> .../userspace-api/media/drivers/hantro.rst    | 19 +++++++++++++++++++
> .../userspace-api/media/drivers/index.rst     |  1 +
> include/media/hevc-ctrls.h                    | 13 +++++++++++++
> 3 files changed, 33 insertions(+)
> create mode 100644 Documentation/userspace-api/media/drivers/hantro.rst
>
>diff --git a/Documentation/userspace-api/media/drivers/hantro.rst b/Documentation/userspace-api/media/drivers/hantro.rst
>new file mode 100644
>index 000000000000..cd9754b4e005
>--- /dev/null
>+++ b/Documentation/userspace-api/media/drivers/hantro.rst
>@@ -0,0 +1,19 @@
>+.. SPDX-License-Identifier: GPL-2.0
>+
>+Hantro video decoder driver
>+===========================
>+
>+The Hantro video decoder driver implements the following driver-specific controls:
>+
>+``V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP (integer)``
>+    Specifies to Hantro HEVC video decoder driver the number of data (in bits) to
>+    skip in the slice segment header.
>+    If non-IDR, the bits to be skipped go from syntax element "pic_output_flag"
>+    to before syntax element "slice_temporal_mvp_enabled_flag".
>+    If IDR, the skipped bits are just "pic_output_flag"
>+    (separate_colour_plane_flag is not supported).

What happens if it is a dependant_slice_segement or
output_flag_present_flag?  Those flags are all dependant on
dependant_slice_segement being false.  I'm guessing 0 but it maybe
should be documented.
Likewise if output_flag_present_flag is false pic_output_flag will not
be coded, so maybe express it as "after slice_type" rather than "before
pic_output_flag"?

Regards

John Cox

>+.. note::
>+
>+        This control is not yet part of the public kernel API and
>+        it is expected to change.
>diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst
>index 1a9038f5f9fa..12e3c512d718 100644
>--- a/Documentation/userspace-api/media/drivers/index.rst
>+++ b/Documentation/userspace-api/media/drivers/index.rst
>@@ -33,6 +33,7 @@ For more details see the file COPYING in the source distribution of Linux.
> 
> 	ccs
> 	cx2341x-uapi
>+        hantro
> 	imx-uapi
> 	max2175
> 	meye-uapi
>diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
>index 8e0109eea454..b713eeed1915 100644
>--- a/include/media/hevc-ctrls.h
>+++ b/include/media/hevc-ctrls.h
>@@ -224,4 +224,17 @@ struct v4l2_ctrl_hevc_decode_params {
> 	__u64	flags;
> };
> 
>+/*  MPEG-class control IDs specific to the Hantro driver as defined by V4L2 */
>+#define V4L2_CID_CODEC_HANTRO_BASE				(V4L2_CTRL_CLASS_CODEC | 0x1200)
>+/*
>+ * V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP -
>+ * the number of data (in bits) to skip in the
>+ * slice segment header.
>+ * If non-IDR, the bits to be skipped go from syntax element "pic_output_flag"
>+ * to before syntax element "slice_temporal_mvp_enabled_flag".
>+ * If IDR, the skipped bits are just "pic_output_flag"
>+ * (separate_colour_plane_flag is not supported).
>+ */
>+#define V4L2_CID_HANTRO_HEVC_SLICE_HEADER_SKIP	(V4L2_CID_CODEC_HANTRO_BASE + 0)
>+
> #endif

  parent reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20 12:10 [PATCH v10 0/9] Add HANTRO G2/HEVC decoder support for IMX8MQ Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 1/9] media: hevc: Add fields and flags for hevc PPS Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 2/9] media: hevc: Add decode params control Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 3/9] media: hantro: change hantro_codec_ops run prototype to return errors Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 4/9] media: hantro: Define HEVC codec profiles and supported features Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 5/9] media: hantro: Only use postproc when post processed formats are defined Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 6/9] media: uapi: Add a control for HANTRO driver Benjamin Gaignard
2021-04-29 13:43   ` Ezequiel Garcia
2021-05-05 14:55   ` Hans Verkuil
2021-05-05 15:20     ` Benjamin Gaignard
2021-05-06 12:50       ` Hans Verkuil
2021-05-06 13:11         ` John Cox
2021-05-06 14:29           ` Nicolas Dufresne
2021-05-16 23:04         ` Ezequiel Garcia
2021-05-18 17:17           ` Nicolas Dufresne
2021-05-05 21:01     ` Ezequiel Garcia
2021-05-05 15:18   ` John Cox [this message]
2021-05-05 15:33     ` Nicolas Dufresne
2021-04-20 12:10 ` [PATCH v10 7/9] media: hantro: handle V4L2_PIX_FMT_HEVC_SLICE control Benjamin Gaignard
2021-04-20 12:10 ` [PATCH v10 8/9] media: hantro: Introduce G2/HEVC decoder Benjamin Gaignard
2021-05-05 14:47   ` Hans Verkuil
2021-04-20 12:10 ` [PATCH v10 9/9] media: hantro: IMX8M: add variant for G2/HEVC codec Benjamin Gaignard
2021-05-05 14:42 ` [PATCH v10 0/9] Add HANTRO G2/HEVC decoder support for IMX8MQ Hans Verkuil
2021-05-25 15:39   ` Hans Verkuil
2021-05-25 16:14     ` Benjamin Gaignard

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