Re: [PATCH 2/2] irqchip/renesas-intc-irqpin: Add R-Car Gen1 fallback binding

[Rob Herring]

On Fri, Dec 09, 2016 at 01:52:20PM +0100, Geert Uytterhoeven wrote:
> Hi Simon,
> 
> On Fri, Dec 9, 2016 at 11:50 AM, Simon Horman
> <horms+renesas@xxxxxxxxxxxx> wrote:
> > In the case of Renesas R-Car hardware we know that there are generations of
> > SoCs, e.g. Gen 1, Gen 2 and Gen 3. But beyond that its not clear what the
> 
> it's
> 
> > relationship between IP blocks might be. For example, I believe that
> > r8a7779 is older than r8a7778 but that doesn't imply that the latter is a
> > descendant of the former or vice versa.
> >
> > We can, however, by examining the documentation and behaviour of the
> > hardware at run-time observe that the current driver implementation appears
> > to be compatible with the IP blocks on SoCs within a given generation.
> >
> > For the above reasons and convenience when enabling new SoCs a
> > per-generation fallback compatibility string scheme being adopted for
> > drivers for Renesas SoCs.
> >
> > Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> > ---
> >  .../interrupt-controller/renesas,intc-irqpin.txt   | 44 ++++++++++++----------
> >  drivers/irqchip/irq-renesas-intc-irqpin.c          |  2 +
> >  2 files changed, 26 insertions(+), 20 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-irqpin.txt b/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-irqpin.txt
> > index 772c550d3b4b..e5a5251be9f5 100644
> > --- a/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-irqpin.txt
> > +++ b/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-irqpin.txt
> > @@ -2,13 +2,19 @@ DT bindings for the R-/SH-Mobile irqpin controller
> >
> >  Required properties:
> >
> > -- compatible: has to be "renesas,intc-irqpin-<soctype>", "renesas,intc-irqpin"
> > -  as fallback.
> > -  Examples with soctypes are:
> > +- compatible:
> >      - "renesas,intc-irqpin-r8a7740" (R-Mobile A1)
> >      - "renesas,intc-irqpin-r8a7778" (R-Car M1A)
> >      - "renesas,intc-irqpin-r8a7779" (R-Car H1)
> >      - "renesas,intc-irqpin-sh73a0" (SH-Mobile AG5)
> > +    - "renesas,rcar-gen1-intc-irqpin" (generic R-Car Gen1 compatible device)
> 
> Does it make sense to add a new family-specific compatible value to a driver
> that's unlikely to receive more users in the future? More recent SoCs use
> renesas,irqc.

If that's the case, then no. Please don't go crazy with your generic 
strings. I don't mind them, but I don't know that I'd call it best 
practice.

Rob