Re: [1/5] i2c: i2c-davinci: switch to use platform_get_irq

[Grygorii Strashko]

On 11/21/2014 04:03 PM, Rob Herring wrote:
> On Fri, Nov 21, 2014 at 5:01 AM, Grygorii Strashko
> <grygorii.strashko@xxxxxx> wrote:
> > On 11/20/2014 11:48 PM, Uwe Kleine-KÃnig wrote:
> > > Hello Grygorii,
> > >
> > > On Thu, Nov 20, 2014 at 12:03:04PM +0200, Grygorii Strashko wrote:
> > > > Switch Davinci I2C driver to use platform_get_irq(), because
> > > > - it is not recommened to use
> > > >     platform_get_resource(pdev, IORESOURCE_IRQ, ..) for requesting IRQ's
> > > >     resources any more, as they can be not ready yet in case of DT-booting.
> > > > - it makes code simpler
> > > >
> > > > CC: Sekhar Nori <nsekhar@xxxxxx>
> > > > CC: Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx>
> > > > CC: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
> > > > CC: Murali Karicheri <m-karicheri2@xxxxxx>
> > > > Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
> > > > ---
> > > >    drivers/i2c/busses/i2c-davinci.c | 14 +++++++-------
> > > >    1 file changed, 7 insertions(+), 7 deletions(-)
> > > >
> > > > diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
> > > > index 4d96147..9bbfb8f 100644
> > > > --- a/drivers/i2c/busses/i2c-davinci.c
> > > > +++ b/drivers/i2c/busses/i2c-davinci.c
> > > > @@ -640,13 +640,13 @@ static int davinci_i2c_probe(struct platform_device *pdev)
> > > >    {
> > > >       struct davinci_i2c_dev *dev;
> > > >       struct i2c_adapter *adap;
> > > > -    struct resource *mem, *irq;
> > > > -    int r;
> > > > +    struct resource *mem;
> > > > +    int r, irq;
> > > >
> > > > -    irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> > > > -    if (!irq) {
> > > > -            dev_err(&pdev->dev, "no irq resource?\n");
> > > > -            return -ENODEV;
> > > > +    irq = platform_get_irq(pdev, 0);
> > > One bad thing about platform_get_irq is its unusual handling of irq=0.
> > > I'm pretty sure you don't want to use this value, so adding something
> > > like:
> > >
> > >        if (!irq)
> > >                irq = -ENXIO

I'll add this check in driver.

> > > would be welcome because the usual value for "invalid irq" is 0 and not
> > > -ESOMETHING. platform_get_irq is one of the very few functions that
> > > don't adhere to this convention. With handling <= 0 as error your code
> > > is immune to changes in this area. Although I notice that
> > > platform_get_irq got worse in this respect to handle -EPROBE_DEFER. hmm.
> > >
> > > Apart from your change I wonder if platform_get_irq should handle
> > > of_irq_get returning 0 as an error.
> >
> > I think you are right and It seems like, the check for !irq should
> > be added/restored for OF case in platform_get_irq() too.
>
> Changing the return values of platform_get_irq is tricky as it would
> potentially break drivers because NO_IRQ can be 0 or -1 depending on
> the arch. Drivers checking against specific values of NO_IRQ would
> break. We've done some clean-up in this area, but I suspect more is
> needed.

Thanks for your comment.

regards,
-grygorii
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/