Re: [PATCH v2 09/10] coresight: Cleanup coresight DT bindings

[Suzuki K Poulose]

On 07/25/2018 05:09 PM, Rob Herring wrote:
> On Thu, Jul 19, 2018 at 11:55:13AM +0100, Suzuki K Poulose wrote:
> > The coresight drivers relied on default bindings for graph
> > in DT, while reusing the "reg" field of the "ports" to indicate
> > the actual hardware port number for the connections. This can
> > cause duplicate ports with same addresses, but different
> > direction. However, with the rules getting stricter w.r.t to the
> > address mismatch with the label, it is no longer possible to use
> > the port address field for the hardware port number.
> >
> > This patch introduces new DT binding rules for coresight
> > components, based on the same generic DT graph bindings, but
> > avoiding the address duplication.
> >
> > - All output ports must be specified under a child node with
> >    name "out-ports".
> > - All input ports must be specified under a childe node with
> >    name "in-ports".
> > - Port address should match the hardware port number.
> >
> > The support for legacy bindings is retained, with a warning.
> >
> > Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> > Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
> > Cc: Rob Herring <robh@xxxxxxxxxx>
> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > ---
> >   .../devicetree/bindings/arm/coresight.txt          | 91 ++++++++++----------
> >   drivers/hwtracing/coresight/of_coresight.c         | 97 +++++++++++++++++++---
> >   2 files changed, 129 insertions(+), 59 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
> > index 8e21512..f39d2c6 100644
> > --- a/Documentation/devicetree/bindings/arm/coresight.txt
> > +++ b/Documentation/devicetree/bindings/arm/coresight.txt
> > @@ -104,19 +104,9 @@ The connections must be described via generic DT graph bindings as described
> >   by the "bindings/graph.txt", where each "port" along with an "endpoint"
> >   component represents a hardware port and the connection.
> >   
> > -Since it is possible to have multiple connections for any coresight component
> > -with a specific direction of data flow, each connection must define the
> > -following properties to uniquely identify the connection details.
> > -
> > - * Direction of the data flow w.r.t the component :
> > -   Each input port must have the following property defined at the "endpoint"
> > -   for the port.
> > -	"slave-mode"
> > -
> > - * Hardware Port number at the component:
> > -     -  The hardware port number is assumed to be the address of the "port"
> > -         component.
> > -
>
> Why do you add this in the previous patch and then remove it here?

The only use case I can think of it is for someone to look back on the
legacy bindings, which were never documented. I could skip the parts 
that are being removed.

Suzuki