RE: [PATCH 1/5] Documentation: dt: binding: fsl: Add 'fsl,ippdexpcr1-alt-addr' property

[Ran Wang]

Hi Rob,

On Monday, September 28, 2020 9:57 PM, Rob Herring wrote:
> 
> On Wed, Sep 23, 2020 at 1:44 AM Ran Wang <ran.wang_1@xxxxxxx> wrote:
> >
> > Hi Rob,
> >
> > On Wednesday, September 23, 2020 10:33 AM, Rob Herring wrote:
> > >
> > > On Wed, Sep 16, 2020 at 04:18:27PM +0800, Ran Wang wrote:
> > > > From: Biwen Li <biwen.li@xxxxxxx>
> > > >
> > > > The 'fsl,ippdexpcr1-alt-addr' property is used to handle an errata
> > > > A-008646 on LS1021A
> > > >
> > > > Signed-off-by: Biwen Li <biwen.li@xxxxxxx>
> > > > Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
> > > > ---
> > > >  Documentation/devicetree/bindings/soc/fsl/rcpm.txt | 19
> > > > +++++++++++++++++++
> > > >  1 file changed, 19 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > b/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > index 5a33619..1be58a3 100644
> > > > --- a/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > +++ b/Documentation/devicetree/bindings/soc/fsl/rcpm.txt
> > > > @@ -34,6 +34,11 @@ Chassis Version          Example Chips
> > > >  Optional properties:
> > > >   - little-endian : RCPM register block is Little Endian. Without it RCPM
> > > >     will be Big Endian (default case).
> > > > + - fsl,ippdexpcr1-alt-addr : The property is related to a hardware issue
> > > > +   on SoC LS1021A and only needed on SoC LS1021A.
> > > > +   Must include 2 entries:
> > > > +   The first entry must be a link to the SCFG device node.
> > > > +   The 2nd entry must be offset of register IPPDEXPCR1 in SCFG.
> > >
> > > You don't need a DT change for this. You can find SCFG node by its
> > > compatible string and then the offset should be known given this issue is
> only on 1 SoC.
> >
> > Did you mean that RCPM driver just to access IPPDEXPCR1 shadowed
> > register in SCFG directly without fetching it's offset info. from DT?
> 
> Yes. There's only 1 possible value of the offset because there's only one SoC, so
> the driver can hardcode the offset. And I assume there's only one SCFG node,
> so you can find it by its compatible string (of_find_compatible_node).

Got it, let me update this in next version, thank you.

Regards,
Ran

> Rob