linux-kernel - [PATCH v9 09/13] media: uapi: Add a control for HANTRO driver

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Message-Id: <20210407073534.376722-10-benjamin.gaignard@collabora.com>
Date:   Wed,  7 Apr 2021 09:35:30 +0200
From:   Benjamin Gaignard <benjamin.gaignard@...labora.com>
To:     ezequiel@...labora.com, p.zabel@...gutronix.de, mchehab@...nel.org,
        robh+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        festevam@...il.com, lee.jones@...aro.org,
        gregkh@...uxfoundation.org, mripard@...nel.org,
        paul.kocialkowski@...tlin.com, wens@...e.org,
        jernej.skrabec@...l.net, hverkuil-cisco@...all.nl,
        emil.l.velikov@...il.com
Cc:     kernel@...gutronix.de, linux-imx@....com,
        linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
        kernel@...labora.com, cphealy@...il.com,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>
Subject: [PATCH v9 09/13] media: uapi: Add a control for HANTRO driver

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@...labora.com>
---
version 9:
 - Corrections in commit message.
 - Move control definition in hevc-ctrls.h
 - Add note in documentation to explain that this control
   may change in the futur

version 5:
 - Be even more verbose in control documentation.
 - Do not create class for the control.
version 4:
- The control is now an integer which is enough to provide the numbers
  of bits to skip.
version 3:
- Fix typo in field name

 .../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).
+
+.. 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
-- 
2.25.1