On 05/06/18 22:43, Suzuki K Poulose wrote:
Coresight uses DT graph bindings to describe the connections of the
components. However we have some undocumented usage of the bindings
to describe some of the properties of the connections.
The coresight driver needs to know the hardware ports invovled
in the connection and the direction of data flow to effectively
manage the trace sessions. So far we have relied on the "port"
address (as described by the generic graph bindings) to represent
the hardware port of the component for a connection.
...
There were three options considered for the hardware port number scheme:
...
3) Use explicit properties (implemented in the series) for the hardware
port id and direction. We define a new property "coresight,hwid" for
each endpoint in coresight devices to specify the hardware port number
explicitly. Also use a separate property "direction" to specify the
direction of the data flow.
e.g,
port@0{
reg = <0>;
endpoint {
direction = <1>; // Output
coresight,hwid = <0>; // Port # 0
}
};
port@1{
reg = <1>;
endpoint {
direction = <0>; // Input
coresight,hwid = <0>; // Port # 0
};
};
Pros:
- The bindings are formal and reader friendly, and less prone to errors.
Cons:
- Backward compatibility is lost.
This series implements Option (3) listed above and falls back to the old
bindings if the new bindings are not available. This allows the systems
with old bindings work with the new driver. The driver now issues a warning
(once) when it encounters the old bindings.
....
dts: juno: Update coresight bindings for hw port
dts: hisilicon: Update coresight bindings for hw ports
dts: spreadtrum: Update coresight bindings for hw ports
dts: qcom: Update coresight bindings for hw ports
dts: arm: hisilicon: Update coresight bindings for hardware port
dts: arm: imx7{d,s}: Update coresight binding for hardware ports
dts: arm: omap: Update coresight bindings for hardware ports
dts: arm: qcom: Update coresight bindings for hardware ports
dts: sama5d2: Update coresight bindings for hardware ports
dts: ste-dbx5x0: Update coresight bindings for hardware port
dts: tc2: Update coresight bindings for hardware ports
All,
Pleas hold on with applying the DTS changes listed above. There are
still some on going discussions on the bindings and we are yet to
come to a conclusion [0]. And there are high chances that these might
change. Sorry for the inconvenience.
[0] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-June/582269.html
Kind regards
Suzuki
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