diff mbox

[RFC,v2,01/15,media] Add common video interfaces OF bindings documentation

Message ID 1356969793-27268-2-git-send-email-s.nawrocki@samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

This patch adds a document describing common OF bindings for video
capture, output and video processing devices. It is curently mainly
focused on video capture devices, with data busses defined by
standards like ITU-R BT.656 or MIPI-CSI2.
It also documents a method of describing data links between devices.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>

---

This is basically a resend of my previous version of this patch [1],
with just a few typo/grammar issue corrections.

[1] http://patchwork.linuxtv.org/patch/15911/
---
 .../devicetree/bindings/media/video-interfaces.txt |  198 ++++++++++++++++++++
 1 file changed, 198 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/media/video-interfaces.txt

Comments

Guennadi Liakhovetski Jan. 2, 2013, 11:31 a.m. UTC | #1
Hi Sylwester

Thanks for picking up these patches! In general both look good to me, just 
a couple of nit-picks, that I couldn't help remarking:-)

On Mon, 31 Dec 2012, Sylwester Nawrocki wrote:

> From: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> 
> This patch adds a document describing common OF bindings for video
> capture, output and video processing devices. It is curently mainly
> focused on video capture devices, with data busses defined by
> standards like ITU-R BT.656 or MIPI-CSI2.
> It also documents a method of describing data links between devices.
> 
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
> Reviewed-by: Stephen Warren <swarren@nvidia.com>
> 
> ---
> 
> This is basically a resend of my previous version of this patch [1],
> with just a few typo/grammar issue corrections.
> 
> [1] http://patchwork.linuxtv.org/patch/15911/
> ---
>  .../devicetree/bindings/media/video-interfaces.txt |  198 ++++++++++++++++++++
>  1 file changed, 198 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/media/video-interfaces.txt
> 
> diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
> new file mode 100644
> index 0000000..d1eea35
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> @@ -0,0 +1,198 @@
> +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 is 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 than 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.

This spacing before ":" looks strange to me. I personally prefer the 
normal English rule - "x: y," i.e. no space before and a space after, but 
I wouldn't remark on your choice of a space on each side in this specific 
case, if it was consistent. Whereas sometimes having one space and 
sometimes having none looks weird to me. I would go for "no space before 
':'" throughout this document.

> +- slave-mode : a boolean property, run the link in slave mode. Default is master
> +  mode.
> +- bus-width : number of data lines, valid for parallel buses.

As we discussed before, both "busses" and "buses" spellings are commonly 
used at different locations around the world, but I think we should stick 
to only one of them in a single document. It looks weird to have "buses" 
in one line and "busses" in the following one.

> +- data-shift: on parallel data busses, if bus-width is used to specify the
> +  number of data lines, data-shift can be used to specify which data lines are
> +  used, e.g. "bus-width=<10>; data-shift=<2>;" means, that lines 9:2 are used.
> +- hsync-active : active state of HSYNC signal, 0/1 for LOW/HIGH respectively.
> +- vsync-active : active state of VSYNC signal, 0/1 for LOW/HIGH respectively.
> +  Note, that if HSYNC and VSYNC polarities are not specified, embedded
> +  synchronization may be required, where supported.
> +- data-active : similar to HSYNC and VSYNC, specifies data line polarity.
> +- field-even-active: field signal level during the even field data transmission.
> +- pclk-sample : rising (1) or falling (0) edge to sample the pixel clock signal.

Yes, it was in my original document too, but don't we mean "sample data on 
rising (1) or falling (0) edge of the pixel clock signal?"

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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Sylwester Nawrocki Jan. 2, 2013, 9:51 p.m. UTC | #2
Hi Guennadi,

On 01/02/2013 12:31 PM, Guennadi Liakhovetski wrote:
> Hi Sylwester
>
> Thanks for picking up these patches! In general both look good to me, just
> a couple of nit-picks, that I couldn't help remarking:-)

Sure, thanks again for the feedback.

> On Mon, 31 Dec 2012, Sylwester Nawrocki wrote:
>
>> From: Guennadi Liakhovetski<g.liakhovetski@gmx.de>
>>
>> This patch adds a document describing common OF bindings for video
>> capture, output and video processing devices. It is curently mainly
>> focused on video capture devices, with data busses defined by
>> standards like ITU-R BT.656 or MIPI-CSI2.
>> It also documents a method of describing data links between devices.
>>
>> Signed-off-by: Guennadi Liakhovetski<g.liakhovetski@gmx.de>
>> Signed-off-by: Sylwester Nawrocki<s.nawrocki@samsung.com>
>> Reviewed-by: Stephen Warren<swarren@nvidia.com>
>>
>> ---
>>
>> This is basically a resend of my previous version of this patch [1],
>> with just a few typo/grammar issue corrections.
>>
>> [1] http://patchwork.linuxtv.org/patch/15911/
>> ---
>>   .../devicetree/bindings/media/video-interfaces.txt |  198 ++++++++++++++++++++
>>   1 file changed, 198 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/media/video-interfaces.txt
>>
>> diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
>> new file mode 100644
>> index 0000000..d1eea35
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
>> @@ -0,0 +1,198 @@
>> +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 is 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 than 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.
>
> This spacing before ":" looks strange to me. I personally prefer the
> normal English rule - "x: y," i.e. no space before and a space after, but
> I wouldn't remark on your choice of a space on each side in this specific
> case, if it was consistent. Whereas sometimes having one space and
> sometimes having none looks weird to me. I would go for "no space before
> ':'" throughout this document.

Gah, it was so close! ;) Sorry about it, it looked more readable to me 
that way.
And I've checked other bindings' documentation and there was many files 
having
space on both sides of a colon. Nevertheless, I will change it back to the
original form.

>> +- slave-mode : a boolean property, run the link in slave mode. Default is master
>> +  mode.
>> +- bus-width : number of data lines, valid for parallel buses.
>
> As we discussed before, both "busses" and "buses" spellings are commonly
> used at different locations around the world, but I think we should stick
> to only one of them in a single document. It looks weird to have "buses"
> in one line and "busses" in the following one.

True, I think that was the one occurrence I'd noticed and have forgotten to
correct then. I'll fix it, thanks for pointing out.

>> +- data-shift: on parallel data busses, if bus-width is used to specify the
>> +  number of data lines, data-shift can be used to specify which data lines are
>> +  used, e.g. "bus-width=<10>; data-shift=<2>;" means, that lines 9:2 are used.
>> +- hsync-active : active state of HSYNC signal, 0/1 for LOW/HIGH respectively.
>> +- vsync-active : active state of VSYNC signal, 0/1 for LOW/HIGH respectively.
>> +  Note, that if HSYNC and VSYNC polarities are not specified, embedded
>> +  synchronization may be required, where supported.
>> +- data-active : similar to HSYNC and VSYNC, specifies data line polarity.
>> +- field-even-active: field signal level during the even field data transmission.
>> +- pclk-sample : rising (1) or falling (0) edge to sample the pixel clock signal.
>
> Yes, it was in my original document too, but don't we mean "sample data on
> rising (1) or falling (0) edge of the pixel clock signal?"

Oops, I've managed to overlooked this. Certainly, it wasn't supposed to mean
sampling the clock signal. BTW, I had some doubts about this property. 
On the
transmitter side we more care about driving, rather than sampling data. And
usually when a transmitter drives data line at one clock edge type (e.g. 
rising)
then the receiver samples data on the other edge (e.g. falling).

In the display timing bindings there is a definitions like:

+ - pixelclk-active: with
+			- active high = drive pixel data on rising edge/
+					sample data on falling edge
+			- active low  = drive pixel data on falling edge/
+					sample data on rising edge
+			- ignored     = ignored

where:

+    <1>: high active
+    <0>: low active
+    omitted: not used on hardware


Then in our case, e.g. pclk-sample = <1>; on the transmitter side would mean
the receiver, which also has same pclk-sample = <1>; specified in its node,
has to sample data on rising clock edge and the transmitter is driving data
on falling edge, right ?

---

Thanks,
Sylwester
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Guennadi Liakhovetski Jan. 2, 2013, 10:01 p.m. UTC | #3
Hi Sylwester

On Wed, 2 Jan 2013, Sylwester Nawrocki wrote:

> Hi Guennadi,
> 
> On 01/02/2013 12:31 PM, Guennadi Liakhovetski wrote:
> > Hi Sylwester
> > 
> > Thanks for picking up these patches! In general both look good to me, just
> > a couple of nit-picks, that I couldn't help remarking:-)
> 
> Sure, thanks again for the feedback.
> 
> > On Mon, 31 Dec 2012, Sylwester Nawrocki wrote:
> > 
> > > From: Guennadi Liakhovetski<g.liakhovetski@gmx.de>
> > > 
> > > This patch adds a document describing common OF bindings for video
> > > capture, output and video processing devices. It is curently mainly
> > > focused on video capture devices, with data busses defined by
> > > standards like ITU-R BT.656 or MIPI-CSI2.
> > > It also documents a method of describing data links between devices.
> > > 
> > > Signed-off-by: Guennadi Liakhovetski<g.liakhovetski@gmx.de>
> > > Signed-off-by: Sylwester Nawrocki<s.nawrocki@samsung.com>
> > > Reviewed-by: Stephen Warren<swarren@nvidia.com>
> > > 
> > > ---
> > > 
> > > This is basically a resend of my previous version of this patch [1],
> > > with just a few typo/grammar issue corrections.
> > > 
> > > [1] http://patchwork.linuxtv.org/patch/15911/
> > > ---
> > >   .../devicetree/bindings/media/video-interfaces.txt |  198
> > > ++++++++++++++++++++
> > >   1 file changed, 198 insertions(+)
> > >   create mode 100644
> > > Documentation/devicetree/bindings/media/video-interfaces.txt
> > > 
> > > diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt
> > > b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > > new file mode 100644
> > > index 0000000..d1eea35
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> > > @@ -0,0 +1,198 @@
> > > +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 is 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 than 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.
> > 
> > This spacing before ":" looks strange to me. I personally prefer the
> > normal English rule - "x: y," i.e. no space before and a space after, but
> > I wouldn't remark on your choice of a space on each side in this specific
> > case, if it was consistent. Whereas sometimes having one space and
> > sometimes having none looks weird to me. I would go for "no space before
> > ':'" throughout this document.
> 
> Gah, it was so close! ;) Sorry about it, it looked more readable to me that
> way.
> And I've checked other bindings' documentation and there was many files having
> space on both sides of a colon. Nevertheless, I will change it back to the
> original form.
> 
> > > +- slave-mode : a boolean property, run the link in slave mode. Default is
> > > master
> > > +  mode.
> > > +- bus-width : number of data lines, valid for parallel buses.
> > 
> > As we discussed before, both "busses" and "buses" spellings are commonly
> > used at different locations around the world, but I think we should stick
> > to only one of them in a single document. It looks weird to have "buses"
> > in one line and "busses" in the following one.
> 
> True, I think that was the one occurrence I'd noticed and have forgotten to
> correct then. I'll fix it, thanks for pointing out.

I think there were at least 2 of them, but I might be wrong, a grep will 
tell with certainty :-)

> > > +- data-shift: on parallel data busses, if bus-width is used to specify
> > > the
> > > +  number of data lines, data-shift can be used to specify which data
> > > lines are
> > > +  used, e.g. "bus-width=<10>; data-shift=<2>;" means, that lines 9:2 are
> > > used.
> > > +- hsync-active : active state of HSYNC signal, 0/1 for LOW/HIGH
> > > respectively.
> > > +- vsync-active : active state of VSYNC signal, 0/1 for LOW/HIGH
> > > respectively.
> > > +  Note, that if HSYNC and VSYNC polarities are not specified, embedded
> > > +  synchronization may be required, where supported.
> > > +- data-active : similar to HSYNC and VSYNC, specifies data line polarity.
> > > +- field-even-active: field signal level during the even field data
> > > transmission.
> > > +- pclk-sample : rising (1) or falling (0) edge to sample the pixel clock
> > > signal.
> > 
> > Yes, it was in my original document too, but don't we mean "sample data on
> > rising (1) or falling (0) edge of the pixel clock signal?"
> 
> Oops, I've managed to overlooked this. Certainly, it wasn't supposed to mean
> sampling the clock signal. BTW, I had some doubts about this property. On the
> transmitter side we more care about driving, rather than sampling data. And
> usually when a transmitter drives data line at one clock edge type (e.g.
> rising)
> then the receiver samples data on the other edge (e.g. falling).
> 
> In the display timing bindings there is a definitions like:
> 
> + - pixelclk-active: with
> +			- active high = drive pixel data on rising edge/
> +					sample data on falling edge
> +			- active low  = drive pixel data on falling edge/
> +					sample data on rising edge
> +			- ignored     = ignored
> 
> where:
> 
> +    <1>: high active
> +    <0>: low active
> +    omitted: not used on hardware
> 
> 
> Then in our case, e.g. pclk-sample = <1>; on the transmitter side would mean
> the receiver, which also has same pclk-sample = <1>; specified in its node,
> has to sample data on rising clock edge and the transmitter is driving data
> on falling edge, right ?

That's also what seems logical to me. We can rephrase it to "should be 
sampled (by the receiver) on the rising edge."

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
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diff mbox

Patch

diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
new file mode 100644
index 0000000..d1eea35
--- /dev/null
+++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
@@ -0,0 +1,198 @@ 
+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 is 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 than 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 : number of data lines, valid for parallel buses.
+- data-shift: on parallel data busses, if bus-width is used to specify the
+  number of data lines, data-shift can be used to specify which data lines are
+  used, e.g. "bus-width=<10>; data-shift=<2>;" means, that lines 9:2 are used.
+- hsync-active : active state of HSYNC signal, 0/1 for LOW/HIGH respectively.
+- vsync-active : active state of VSYNC signal, 0/1 for LOW/HIGH respectively.
+  Note, that if HSYNC and VSYNC polarities are not specified, embedded
+  synchronization may be required, where supported.
+- data-active : similar to HSYNC and VSYNC, specifies data line polarity.
+- field-even-active: field signal level during the even field data transmission.
+- pclk-sample : rising (1) or falling (0) edge to sample the pixel clock signal.
+- data-lanes : an array of physical data lane indexes. Position of an entry
+  determines logical lane number, while the value of an entry indicates physical
+  lane, e.g. for 2-lane MIPI CSI-2 bus we could have "data-lanes = <1>, <2>;",
+  assuming the clock lane is on hardware lane 0. This property is valid for
+  serial buses only (e.g. MIPI CSI-2).
+- clock-lanes : a number of physical lane used as a clock lane.
+- clock-noncontinuous : a boolean property to allow MIPI CSI-2 non-continuous
+  clock mode.
+
+Example
+-------
+
+The below example snippet describes two data pipelines.  ov772x and imx074 are
+camera sensors with parallel and serial (MIPI CSI-2) video bus respectively.
+Both sensors are on I2C control bus corresponding to i2c0 controller node.
+ov772x sensor is linked directly to the ceu0 video host interface.  imx074 is
+linked to ceu0 through MIPI CSI-2 receiver (csi2). ceu0 has a (single) DMA
+engine writing captured data to memory.  ceu0 node has single 'port' node which
+indicates at any time only one of following data pipeline can be active:
+ov772x -> ceu0 or imx074 -> csi2 -> ceu0.
+
+	ceu0: ceu@0xfe910000 {
+		compatible = "renesas,sh-mobile-ceu";
+		reg = <0xfe910000 0xa0>;
+		interrupts = <0x880>;
+
+		mclk: master_clock {
+			compatible = "renesas,ceu-clock";
+			#clock-cells = <1>;
+			clock-frequency = <50000000>;	/* Max clock frequency */
+			clock-output-names = "mclk";
+		};
+
+		port {
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			ceu0_1: endpoint@1 {
+				reg = <1>;		/* Local endpoint # */
+				remote = <&ov772x_1_1>;	/* Remote phandle */
+				bus-width = <8>;	/* Used data lines */
+				data-shift = <0>;	/* Lines 7:0 are used */
+
+				/* If hsync-active/vsync-active are missing,
+				   embedded bt.605 sync is used */
+				hsync-active = <1>;	/* Active high */
+				vsync-active = <1>;	/* Active high */
+				data-active = <1>;	/* Active high */
+				pclk-sample = <1>;	/* Rising */
+			};
+
+			ceu0_0: endpoint@0 {
+				reg = <0>;
+				remote = <&csi2_2>;
+				immutable;
+			};
+		};
+	};
+
+	i2c0: i2c@0xfff20000 {
+		...
+		ov772x_1: camera@0x21 {
+			compatible = "omnivision,ov772x";
+			reg = <0x21>;
+			vddio-supply = <&regulator1>;
+			vddcore-supply = <&regulator2>;
+
+			clock-frequency = <20000000>;
+			clocks = <&mclk 0>;
+			clock-names = "xclk";
+
+			port {
+				/* With 1 endpoint per port no need in addresses. */
+				ov772x_1_1: endpoint {
+					bus-width = <8>;
+					remote-endpoint = <&ceu0_1>;
+					hsync-active = <1>;
+					vsync-active = <0>; /* Who came up with an
+							       inverter here ?... */
+					data-active = <1>;
+					pclk-sample = <1>;
+				};
+			};
+		};
+
+		imx074: camera@0x1a {
+			compatible = "sony,imx074";
+			reg = <0x1a>;
+			vddio-supply = <&regulator1>;
+			vddcore-supply = <&regulator2>;
+
+			clock-frequency = <30000000>;	/* Shared clock with ov772x_1 */
+			clocks = <&mclk 0>;
+			clock-names = "sysclk";		/* Assuming this is the
+							   name in the datasheet */
+			port {
+				imx074_1: endpoint {
+					clock-lanes = <0>;
+					data-lanes = <1>, <2>;
+					remote-endpoint = <&csi2_1>;
+				};
+			};
+		};
+	};
+
+	csi2: csi2@0xffc90000 {
+		compatible = "renesas,sh-mobile-csi2";
+		reg = <0xffc90000 0x1000>;
+		interrupts = <0x17a0>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		port@1 {
+			compatible = "renesas,csi2c";	/* One of CSI2I and CSI2C. */
+			reg = <1>;			/* CSI-2 PHY #1 of 2: PHY_S,
+							   PHY_M has port address 0,
+							   is unused. */
+			csi2_1: endpoint {
+				clock-lanes = <0>;
+				data-lanes = <2>, <1>;
+				remote-endpoint = <&imx074_1>;
+			};
+		};
+		port@2 {
+			reg = <2>;			/* port 2: link to the CEU */
+
+			csi2_2: endpoint {
+				immutable;
+				remote-endpoint = <&ceu0_0>;
+			};
+		};
+	};