On 12/15/2012 03:13 PM, Sylwester Nawrocki wrote:
From: Guennadi Liakhovetski g.liakhovet...@gmx.de
This patch adds a document describing common OF bindings for video
capture, output and video processing devices. It is currently mainly
focused on video capture devices, with data interfaces defined in
standards like ITU-R BT.656 or MIPI CSI-2.
It also documents a method of describing data links between devices.
Signed-off-by: Guennadi Liakhovetski g.liakhovet...@gmx.de
Signed-off-by: Sylwester Nawrocki s.nawro...@samsung.com
Looks reasonable. You can merge this with the rest of the series.
Acked-by: Rob Herring rob.herr...@calxeda.com
---
Hi,
This is an updated version of patch [1]. My changes include resolving
issues pointed out during review, i.e.:
- renaming 'link' node to 'endpoint,
- renaming 'remote' phandle to 'remote-endpoint',
- file v4l2.txt renamed to video-interfaces.txt,
- removed references to V4L2,
- added short description of the example DT snippet
and additionally:
- added Required properties' paragraph,
- updated description of 'data-lanes' property,
- renamed all erroneous occurrences of 'data-width' to 'bus-width',
- added 'bus-width' property description,
- modified description of hsync-active, vsync-active properties,
- added a little paragraph further explaining that each endpoint
node has properties determining configuration of its corresponding
device.
[1] https://patchwork.kernel.org/patch/1514381/
I'm still unsure about the first sentence, as these bindings can be
used for describing SoC internal connections between modules as well.
I was considering adding something like:
This document describes common bindings for video capture, processing
and output devices using data buses defined in standards like ITU-R
BT.656, MIPI CSI-2,...
before the General concept paragraph.
And maybe Documentation/devicetree/bindings/video/ would a better place
for this video-interfaces.txt file ?
Thanks,
Sylwester
---
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Documentation/devicetree/bindings/media/video-interfaces.txt
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+Common bindings for video data receiver and transmitter interfaces
+
+General concept
+---
+
+Video data pipelines usually consist of external devices, e.g. camera
sensors,
+controlled over an I2C, SPI or UART bus, and SoC internal IP blocks,
including
+video DMA engines and video data processors.
+
+SoC internal blocks are described by DT nodes, placed similarly to other SoC
+blocks. External devices are represented as child nodes of their respective
+bus controller nodes, e.g. I2C.
+
+Data interfaces on all video devices are described by their child 'port'
nodes.
+Configuration of a port depends on other devices participating in the data
+transfer and is described by 'endpoint' subnodes.
+
+dev {
+ #address-cells = 1;
+ #size-cells = 0;
+ port@0 {
+ endpoint@0 { ... };
+ endpoint@1 { ... };
+ };
+ port@1 { ... };
+};
+
+If a port can be configured to work with more than one other device on the
same
+bus, an 'endpoint' child node must be provided for each of them. If more
than
+one port is present in a device node or there is more than one endpoint at a
+port, a common scheme, using '#address-cells', '#size-cells' and 'reg'
properties
+is used.
+
+Two 'endpoint' nodes are linked with each other through their
'remote-endpoint'
+phandles. An endpoint subnode of a device contains all properties needed for
+configuration of this device for data exchange with the other device. In
most
+cases properties at the peer 'endpoint' nodes will be identical, however
+they might need to be different when there are any signal modifications on
the
+bus between two devices, e.g. there are logic signal inverters on the lines.
+
+Required properties
+---
+
+If there is more that one 'port' or more than one 'endpoint' node following
+properties are required in relevant parent node:
+
+- #address-cells : number of cells required to define port number, should be
1.
+- #size-cells: should be zero.
+
+Optional endpoint properties
+
+
+- remote-endpoint : phandle to an 'endpoint' subnode of the other device
node.
+- slave-mode : a boolean property, run the link in slave mode. Default is
master
+ mode.
+- bus-width : the number of data lines, valid for parallel buses.
+- data-shift: on parallel data busses, if bus-width is used to specify the
+
