| Message ID | 1393522540-22887-3-git-send-email-p.zabel@pengutronix.de |
|---|---|
| State | Superseded, archived |
| Headers | show |
Hi Philipp, Just couple minor comments... On 02/27/2014 06:35 PM, Philipp Zabel wrote: > The device tree graph bindings as used by V4L2 and documented in > Documentation/device-tree/bindings/media/video-interfaces.txt contain > generic parts that are not media specific but could be useful for any > subsystem with data flow between multiple devices. This document > describe the generic bindings. s/describe/describes/ > Signed-off-by: Philipp Zabel<p.zabel@pengutronix.de> > --- > Changes since v4: > - Differentiate from graphs made by simple phandle links > - Do not mention data flow except in video-interfaces example > - > --- > Documentation/devicetree/bindings/graph.txt | 129 ++++++++++++++++++++++++++++ > 1 file changed, 129 insertions(+) > create mode 100644 Documentation/devicetree/bindings/graph.txt > > diff --git a/Documentation/devicetree/bindings/graph.txt b/Documentation/devicetree/bindings/graph.txt > new file mode 100644 > index 0000000..554865b > --- /dev/null > +++ b/Documentation/devicetree/bindings/graph.txt > @@ -0,0 +1,129 @@ > +Common bindings for device graphs > + > +General concept > +--------------- > + > +The hierarchical organisation of the device tree is well suited to describe > +control flow to devices, but there can be more complex connections between > +devices that work together to form a logical compound device, following an > +arbitrarily complex graph. > +There already is a simple directed graph between devices tree nodes using > +phandle properties pointing to other nodes to describe connections that > +can not be inferred from device tree parent-child relationships. The device > +tree graph bindings described herein abstract more complex devices that can > +have multiple specifiable ports, each of which can be linked to one or more > +ports of other devices. > + > +These common bindings do not contain any information about the direction of s/of/or/ ? > +type of the connections, they just map their existence. Specific properties > +may be described by specialized bindings depending on the type of connection. > + > +To see how this binding applies to video pipelines, for example, see > +Documentation/device-tree/bindings/media/video-interfaces.txt. > +Here the ports describe data interfaces, and the links between them are > +the connecting data buses. A single port with multiple connections can > +correspond to multiple devices being connected to the same physical bus. > + > +Organisation of ports and endpoints > +----------------------------------- > + > +Ports are described by child 'port' nodes contained in the device node. > +Each port node contains an 'endpoint' subnode for each remote device port > +connected to this port. If a single port is connected to more than one > +remote device, an 'endpoint' child node must be provided for each link. > +If more than one port is present in a device node or there is more than one > +endpoint at a port, or a port node needs to be associated with a selected > +hardware interface, a common scheme using '#address-cells', '#size-cells' > +and 'reg' properties is used number the nodes. > + > +device { > + ... > + #address-cells =<1>; > + #size-cells =<0>; > + > + port@0 { > + #address-cells =<1>; > + #size-cells =<0>; > + reg =<0>; > + > + endpoint@0 { > + reg =<0>; > + ... > + }; > + endpoint@1 { > + reg =<1>; > + ... > + }; > + }; > + > + port@1 { > + reg =<1>; > + > + endpoint { ... }; > + }; > +}; > + > +All 'port' nodes can be grouped under an optional 'ports' node, which > +allows to specify #address-cells, #size-cells properties for the 'port' > +nodes independently from any other child device nodes a device might > +have. > + > +device { > + ... > + ports { > + #address-cells =<1>; > + #size-cells =<0>; > + > + port@0 { > + ... > + endpoint@0 { ... }; > + endpoint@1 { ... }; > + }; > + > + port@1 { ... }; > + }; > +}; > + > +Links between endpoints > +----------------------- > + > +Each endpoint should contain a 'remote-endpoint' phandle property that points > +to the corresponding endpoint in the port of the remote device. In turn, the > +remote endpoint should contain a 'remote-endpoint' property. If it has one, > +it must not point to another than the local endpoint. Two endpoints with their > +'remote-endpoint' phandles pointing at each other form a link between the > +containing ports. > + > +device_1 { > + port { > + device_1_output: endpoint { > + remote-endpoint =<&device_2_input>; > + }; > + }; > +}; > + > +device_1 { s/device_1/device_2/ But it might be better to use dashes instead of underscores for the node names. > + port { > + device_2_input: endpoint { > + remote-endpoint =<&device_1_output>; > + }; > + }; > +}; > + > + > +Required properties > +------------------- > + > +If there is more than one 'port' or more than one 'endpoint' node or 'reg' > +property is present in port and/or endpoint nodes the following properties > +are required in a relevant parent node: > + > + - #address-cells : number of cells required to define port/endpoint > + identifier, should be 1. > + - #size-cells : should be zero. > + > +Optional endpoint properties > +---------------------------- > + > +- remote-endpoint: phandle to an 'endpoint' subnode of a remote device node. > + -- Regards, Sylwester -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Sylwester, Am Freitag, den 28.02.2014, 22:08 +0100 schrieb Sylwester Nawrocki: > Hi Philipp, > > Just couple minor comments... Thanks, I'll fix all of those. > On 02/27/2014 06:35 PM, Philipp Zabel wrote: > > The device tree graph bindings as used by V4L2 and documented in > > Documentation/device-tree/bindings/media/video-interfaces.txt contain > > generic parts that are not media specific but could be useful for any > > subsystem with data flow between multiple devices. This document > > describe the generic bindings. > > s/describe/describes/ [...] > > +These common bindings do not contain any information about the direction of > > s/of/or/ ? [...] > > +device_1 { > > + port { > > + device_1_output: endpoint { > > + remote-endpoint =<&device_2_input>; > > + }; > > + }; > > +}; > > + > > +device_1 { > > s/device_1/device_2/ > But it might be better to use dashes instead of underscores > for the node names. regards Philipp -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/graph.txt b/Documentation/devicetree/bindings/graph.txt new file mode 100644 index 0000000..554865b --- /dev/null +++ b/Documentation/devicetree/bindings/graph.txt @@ -0,0 +1,129 @@ +Common bindings for device graphs + +General concept +--------------- + +The hierarchical organisation of the device tree is well suited to describe +control flow to devices, but there can be more complex connections between +devices that work together to form a logical compound device, following an +arbitrarily complex graph. +There already is a simple directed graph between devices tree nodes using +phandle properties pointing to other nodes to describe connections that +can not be inferred from device tree parent-child relationships. The device +tree graph bindings described herein abstract more complex devices that can +have multiple specifiable ports, each of which can be linked to one or more +ports of other devices. + +These common bindings do not contain any information about the direction of +type of the connections, they just map their existence. Specific properties +may be described by specialized bindings depending on the type of connection. + +To see how this binding applies to video pipelines, for example, see +Documentation/device-tree/bindings/media/video-interfaces.txt. +Here the ports describe data interfaces, and the links between them are +the connecting data buses. A single port with multiple connections can +correspond to multiple devices being connected to the same physical bus. + +Organisation of ports and endpoints +----------------------------------- + +Ports are described by child 'port' nodes contained in the device node. +Each port node contains an 'endpoint' subnode for each remote device port +connected to this port. If a single port is connected to more than one +remote device, an 'endpoint' child node must be provided for each link. +If more than one port is present in a device node or there is more than one +endpoint at a port, or a port node needs to be associated with a selected +hardware interface, a common scheme using '#address-cells', '#size-cells' +and 'reg' properties is used number the nodes. + +device { + ... + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + #address-cells = <1>; + #size-cells = <0>; + reg = <0>; + + endpoint@0 { + reg = <0>; + ... + }; + endpoint@1 { + reg = <1>; + ... + }; + }; + + port@1 { + reg = <1>; + + endpoint { ... }; + }; +}; + +All 'port' nodes can be grouped under an optional 'ports' node, which +allows to specify #address-cells, #size-cells properties for the 'port' +nodes independently from any other child device nodes a device might +have. + +device { + ... + ports { + #address-cells = <1>; + #size-cells = <0>; + + port@0 { + ... + endpoint@0 { ... }; + endpoint@1 { ... }; + }; + + port@1 { ... }; + }; +}; + +Links between endpoints +----------------------- + +Each endpoint should contain a 'remote-endpoint' phandle property that points +to the corresponding endpoint in the port of the remote device. In turn, the +remote endpoint should contain a 'remote-endpoint' property. If it has one, +it must not point to another than the local endpoint. Two endpoints with their +'remote-endpoint' phandles pointing at each other form a link between the +containing ports. + +device_1 { + port { + device_1_output: endpoint { + remote-endpoint = <&device_2_input>; + }; + }; +}; + +device_1 { + port { + device_2_input: endpoint { + remote-endpoint = <&device_1_output>; + }; + }; +}; + + +Required properties +------------------- + +If there is more than one 'port' or more than one 'endpoint' node or 'reg' +property is present in port and/or endpoint nodes the following properties +are required in a relevant parent node: + + - #address-cells : number of cells required to define port/endpoint + identifier, should be 1. + - #size-cells : should be zero. + +Optional endpoint properties +---------------------------- + +- remote-endpoint: phandle to an 'endpoint' subnode of a remote device node. +
The device tree graph bindings as used by V4L2 and documented in Documentation/device-tree/bindings/media/video-interfaces.txt contain generic parts that are not media specific but could be useful for any subsystem with data flow between multiple devices. This document describe the generic bindings. Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de> --- Changes since v4: - Differentiate from graphs made by simple phandle links - Do not mention data flow except in video-interfaces example - --- Documentation/devicetree/bindings/graph.txt | 129 ++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 Documentation/devicetree/bindings/graph.txt