linux-kernel - Re: [PATCH v11 3/5] media: Documentation: aspeed-video: Add user documentation for the aspeed-video driver

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Message-ID: <Y4oKnBDnvliD8cJb@paasikivi.fi.intel.com>
Date:   Fri, 2 Dec 2022 14:24:28 +0000
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Jammy Huang <jammy_huang@...eedtech.com>
Cc:     eajames@...ux.ibm.com, mchehab@...nel.org, joel@....id.au,
        andrew@...id.au, hverkuil-cisco@...all.nl,
        laurent.pinchart@...asonboard.com, xavier.roumegue@....nxp.com,
        ezequiel@...guardiasur.com.ar, stanimir.varbanov@...aro.org,
        nicolas.dufresne@...labora.com, ming.qian@....com,
        andrzej.p@...labora.com, linux-media@...r.kernel.org,
        openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v11 3/5] media: Documentation: aspeed-video: Add user
 documentation for the aspeed-video driver

Hi Jammy,

On Fri, Oct 28, 2022 at 10:35:52AM +0800, Jammy Huang wrote:
> Add user documentation for the aspeed-video driver.
> 
> Signed-off-by: Jammy Huang <jammy_huang@...eedtech.com>
> ---
> v11:
>   - update the way to change format
> v10:
>   - new
> ---
>  .../media/drivers/aspeed-video.rst            | 61 +++++++++++++++++++
>  .../userspace-api/media/drivers/index.rst     |  1 +
>  2 files changed, 66 insertions(+)
>  create mode 100644 Documentation/userspace-api/media/drivers/aspeed-video.rst
> 
> diff --git a/Documentation/userspace-api/media/drivers/aspeed-video.rst b/Documentation/userspace-api/media/drivers/aspeed-video.rst
> new file mode 100644
> index 000000000000..e5656a8d990e
> --- /dev/null
> +++ b/Documentation/userspace-api/media/drivers/aspeed-video.rst
> @@ -0,0 +1,65 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +.. include:: <isonum.txt>
> +
> +ASPEED video driver
> +===================
> +
> +ASPEED Video Engine found on AST2400/2500/2600 SoC supports high performance
> +video compressions with a wide range of video quality and compression ratio
> +options. The adopted compressing algorithm is a modified JPEG algorithm.
> +
> +There are 2 types of compressions in this IP.
> +
> +* JPEG JFIF standard mode: for single frame and management compression
> +* ASPEED proprietary mode: for multi-frame and differential compression.
> +  Support 2-pass (high quality) video compression scheme (Patent pending by
> +  ASPEED). Provide visually lossless video compression quality or to reduce
> +  the network average loading under intranet KVM applications.
> +
> +VIDIOC_S_FMT can be used to choose which format you want. V4L2_PIX_FMT_JPEG
> +stands for JPEG JFIF standard mode; V4L2_PIX_FMT_AJPG stands for ASPEED
> +proprietary mode.
> +
> +More details on the ASPEED video hardware operations can be found in
> +*chapter 6.2.16 KVM Video Driver* of SDK_User_Guide which available on
> +AspeedTech-BMC/openbmc/releases.

Same comment on this, what does this refer to?

> +
> +The ASPEED video driver implements the following driver-specific control:
> +
> +``V4L2_CID_ASPEED_HQ_MODE``
> +-------------------------------
> +    Enable/Disable ASPEED's High quality mode. This is a private control
> +    that can be used to enable high quality for aspeed proprietary mode.
> +
> +.. flat-table::
> +    :header-rows:  0
> +    :stub-columns: 0
> +    :widths:       1 4
> +
> +    * - ``(0)``
> +      - ASPEED HQ mode is disabled.
> +    * - ``(1)``
> +      - ASPEED HQ mode is enabled.
> +
> +``V4L2_CID_ASPEED_HQ_JPEG_QUALITY``
> +-------------------------------
> +    Define the quality of ASPEED's High quality mode. This is a private control
> +    that can be used to decide compression quality if High quality mode enabled
> +    . Higher the value, better the quality and bigger the size.
> +
> +.. flat-table::
> +    :header-rows:  0
> +    :stub-columns: 0
> +    :widths:       1 4
> +
> +    * - ``(1)``
> +      - minimum
> +    * - ``(12)``
> +      - maximum
> +    * - ``(1)``
> +      - step
> +    * - ``(1)``
> +      - default
> +
> +**Copyright** |copy| 2022 ASPEED Technology Inc.
> diff --git a/Documentation/userspace-api/media/drivers/index.rst b/Documentation/userspace-api/media/drivers/index.rst
> index 32f82aed47d9..46a494e00b72 100644
> --- a/Documentation/userspace-api/media/drivers/index.rst
> +++ b/Documentation/userspace-api/media/drivers/index.rst
> @@ -31,6 +31,7 @@ For more details see the file COPYING in the source distribution of Linux.
>  	:maxdepth: 5
>  	:numbered:
>  
> +	aspeed-video
>  	ccs
>  	cx2341x-uapi
>  	dw100

-- 
Kind regards,

Sakari Ailus