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

From: Jammy Huang
Date: Thu Oct 27 2022 - 22:38:39 EST


Add user documentation for the aspeed-video driver.

Signed-off-by: Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>
---
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.
+
+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
--
2.25.1