Re: [PATCH] pinctrl: baytrail: explicitly set gpio chip base

[Antonio Ospite <ao2@xxxxxx>]

Hi Mika,

On Thu, 30 Apr 2015 14:02:37 +0300
Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote:

> On Wed, Apr 29, 2015 at 11:02:42AM +0200, Antonio Ospite wrote:
> > Having the gpio chip base set explicitly makes it easier to compare the
> > GPIOs definitions with the ones found on some Android kernels.
> > 
> > Signed-off-by: Antonio Ospite <ao2@xxxxxx>
> > Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > Cc: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> > Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> > Cc: linux-gpio@xxxxxxxxxxxxxxx
> > ---
> >  drivers/pinctrl/intel/pinctrl-baytrail.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/pinctrl/intel/pinctrl-baytrail.c b/drivers/pinctrl/intel/pinctrl-baytrail.c
> > index 2062c22..4b2f594 100644
> > --- a/drivers/pinctrl/intel/pinctrl-baytrail.c
> > +++ b/drivers/pinctrl/intel/pinctrl-baytrail.c
> > @@ -548,6 +548,7 @@ static int byt_gpio_probe(struct platform_device *pdev)
> >  	struct acpi_device *acpi_dev;
> >  	struct pinctrl_gpio_range *range;
> >  	acpi_handle handle = ACPI_HANDLE(dev);
> > +	int base_offset;
> >  	int ret;
> >  
> >  	if (acpi_bus_get_device(handle, &acpi_dev))
> > @@ -559,12 +560,14 @@ static int byt_gpio_probe(struct platform_device *pdev)
> >  		return -ENOMEM;
> >  	}
> >  
> > +	base_offset = 0;
> >  	for (range = byt_ranges; range->name; range++) {
> >  		if (!strcmp(acpi_dev->pnp.unique_id, range->name)) {
> >  			vg->chip.ngpio = range->npins;
> >  			vg->range = range;
> >  			break;
> >  		}
> > +		base_offset += range->npins;
> >  	}
> >  
> >  	if (!vg->chip.ngpio || !vg->range)
> > @@ -590,7 +593,7 @@ static int byt_gpio_probe(struct platform_device *pdev)
> >  	gc->get = byt_gpio_get;
> >  	gc->set = byt_gpio_set;
> >  	gc->dbg_show = byt_gpio_dbg_show;
> > -	gc->base = -1;
> > +	gc->base = base_offset;
> 
> But this changes the base from being dynamically allocated to always
> start from 0, right?
>

Yes, that's the point: to have exactly the same bases as in the Android
kernels found in the wild, that is:

  $ ls -1 /sys/class/gpio
  export
  gpiochip0
  gpiochip102
  gpiochip130
  unexport

This makes it easier for me to verify the mappings when trying to make
my tablet work with the mainline kernel.

I might as well keep the change local, but I thought that others may
find it useful.

Are there drawbacks of such fixed scheme?

Ciao,
   Antonio

> >  	gc->can_sleep = false;
> >  	gc->dev = dev;
> >  
> > -- 
> > 2.1.4


-- 
Antonio Ospite
http://ao2.it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?
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