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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,
        kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com,
        gregkh@linuxfoundation.org, mripard@kernel.org,
        paul.kocialkowski@bootlin.com, wens@csie.org,
        jernej.skrabec@siol.net, peng.fan@nxp.com,
        hverkuil-cisco@xs4all.nl, dan.carpenter@oracle.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, kernel@collabora.com,
        Benjamin Gaignard <benjamin.gaignard@collabora.com>
Subject: Re: [PATCH v2 4/9] media: uapi: Add a control for HANTRO driver
Date:   Mon, 22 Feb 2021 16:16:39 +0000
Message-ID: <9ql73glgbnjaqqsp8ulqenae5n82kfk0o3@4ax.com>
References: <20210218191844.297869-1-benjamin.gaignard@collabora.com> <20210218191844.297869-5-benjamin.gaignard@collabora.com>
In-Reply-To: <20210218191844.297869-5-benjamin.gaignard@collabora.com>
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>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
>that this purpose.
>
>Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>---
> include/uapi/linux/hantro-v4l2-controls.h | 20 ++++++++++++++++++++
> include/uapi/linux/v4l2-controls.h        |  5 +++++
> 2 files changed, 25 insertions(+)
> create mode 100644 include/uapi/linux/hantro-v4l2-controls.h
>
>diff --git a/include/uapi/linux/hantro-v4l2-controls.h =
b/include/uapi/linux/hantro-v4l2-controls.h
>new file mode 100644
>index 000000000000..30b1999b7af3
>--- /dev/null
>+++ b/include/uapi/linux/hantro-v4l2-controls.h
>@@ -0,0 +1,20 @@
>+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
>+
>+#ifndef __UAPI_HANTRO_V4L2_CONYTROLS_H__
>+#define __UAPI_HANTRO_V4L2_CONYTROLS_H__
>+
>+#include <linux/v4l2-controls.h>
>+#include <media/hevc-ctrls.h>
>+
>+#define V4L2_CID_HANTRO_HEVC_EXTRA_DECODE_PARAMS	=
(V4L2_CID_USER_HANTRO_BASE + 0)
>+
>+/**
>+ * struct hantro_hevc_extra_decode_params - extra decode parameters for=
 hantro driver
>+ * @hevc_hdr_skip_lenght:	header first bits offset
>+ */
>+struct hantro_hevc_extra_decode_params {
>+	__u32	hevc_hdr_skip_lenght;
>+	__u8	padding[4];
>+};

Can you clarify how hevc_hdr_skip_length differs from
v4l2_ctrl_hevc_slice_params.data_bit_offset?  At first sight they would
appear to be very similar.

Regards

John Cox

>+#endif
>diff --git a/include/uapi/linux/v4l2-controls.h =
b/include/uapi/linux/v4l2-controls.h
>index 039c0d7add1b..ced7486c7f46 100644
>--- a/include/uapi/linux/v4l2-controls.h
>+++ b/include/uapi/linux/v4l2-controls.h
>@@ -209,6 +209,11 @@ enum v4l2_colorfx {
>  * We reserve 128 controls for this driver.
>  */
> #define V4L2_CID_USER_CCS_BASE			(V4L2_CID_USER_BASE + 0x10f0)
>+/*
>+ * The base for HANTRO driver controls.
>+ * We reserve 32 controls for this driver.
>+ */
>+#define V4L2_CID_USER_HANTRO_BASE		(V4L2_CID_USER_BASE + 0x1170)
>=20
> /* MPEG-class control IDs */
> /* The MPEG controls are applicable to all codec controls