Re: [PATCH v3] irqchip: renesas-intc-irqpin: DT binding for sense bitfield width

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Guennadi,

On Monday 08 April 2013 13:25:46 Guennadi Liakhovetski wrote:
> On Mon, 8 Apr 2013, Laurent Pinchart wrote:
> > On Monday 08 April 2013 10:08:40 Guennadi Liakhovetski wrote:
> > > Most Renesas irqpin controllers have 4-bit sense fields, however, some
> > > have different widths. This patch adds a DT binding to optionally
> > > specify such non-standard values.
> > > 
> > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
> > > ---
> > > 
> > > v3: move the code to a common location, where device configuration
> > > parameters are retrieved
> > > 
> > >  .../interrupt-controller/renesas,intc-irqpin.txt   |   13 +++++++++++++
> > >  drivers/irqchip/irq-renesas-intc-irqpin.c          |    4 ++++
> > >  2 files changed, 17 insertions(+), 0 deletions(-)
> > >  create mode 100644
> > > 
> > > Documentation/devicetree/bindings/interrupt-controller/renesas,intc-
> > > irqpin.txt
> > > diff --git a/Documentation/devicetree/bindings/interrupt-
> > > controller/renesas,intc-irqpin.txt
> > > b/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-
> > > irqpin.txt
> > > new file mode 100644
> > > index 0000000..c6f09b7
> > > --- /dev/null
> > > +++
> > > b/Documentation/devicetree/bindings/interrupt-controller/renesas,intc-
> > > irqpin.txt
> > > @@ -0,0 +1,13 @@
> > > +DT bindings for the R-/SH-Mobile irqpin controller
> > > +
> > > +Required properties:
> > > +
> > > +- compatible: has to be "renesas,intc-irqpin"
> > > +- #interrupt-cells: has to be <2>
> > > +
> > > +Optional properties:
> > > +
> > > +- any properties, listed in interrupts.txt in this directory, and any
> > > standard
> > > +  resource allocation properties
> > > +- sense-bitfield-width: width of a single sense bitfield in the SENSE
> > > register,
> > > +  if different from the default 4 bits
> > 
> > Wouldn't it be better to define per-SoC compatible strings, and infer the
> > sense bitfield width from that ?
> 
> This is not a boolean, it is an integer, I don't think defining
> compatibility strings for 1, 2, 3, 4, 5,... bits is better than having one
> integer property.

I'm not advocating for compatibility strings for a given number of bits, but 
for per-SoC compatibility strings from which to infer the width.

For instance, if the r8a7779 has a 6-bit sense field, you would use

compatible = "r8a7779,intc-irqpin";

and map that to 6 in the irqpin driver.

> > > diff --git a/drivers/irqchip/irq-renesas-intc-irqpin.c
> > > b/drivers/irqchip/irq-renesas-intc-irqpin.c index 5a68e5a..4aca1b2
> > > 100644
> > > --- a/drivers/irqchip/irq-renesas-intc-irqpin.c
> > > +++ b/drivers/irqchip/irq-renesas-intc-irqpin.c
> > > @@ -18,6 +18,7 @@
	> > >   */
> > >  
> > >  #include <linux/init.h>
> > > +#include <linux/of.h>
> > >  #include <linux/platform_device.h>
> > >  #include <linux/spinlock.h>
> > >  #include <linux/interrupt.h>
> > > 
> > > @@ -349,6 +350,9 @@ static int intc_irqpin_probe(struct platform_device
> > > *pdev) /* deal with driver instance configuration */
> > >  	if (pdata)
> > >  		memcpy(&p->config, pdata, sizeof(*pdata));
> > > +	else
> > > +		of_property_read_u32(pdev->dev.of_node, "sense-bitfield-width",
> > > +				     &p->config.sense_bitfield_width);
> > > 
> > >  	if (!p->config.sense_bitfield_width)
> > >  		p->config.sense_bitfield_width = 4; /* default to 4 bits */

-- 
Regards,

Laurent Pinchart