Re: [PATCH v2 1/3] pwm: Add pwm_cansleep() as exported API to users

[Florian Vaussard]

Hello,

Le 28/01/2013 09:45, Peter Ujfalusi a Ãcrit :
> hi Thierry,
>
> On 01/26/2013 06:40 AM, Thierry Reding wrote:
> > > +  * @pwm: PWM device
> > > +  *
> > > +  * It returns nonzero if accessing the PWM can sleep.
> > > +  */
> > > +int pwm_cansleep(struct pwm_device *pwm)
> >
> > I actually liked pwm_can_sleep() better. I find it to be more consistent
> > with the naming of other function names. It would furthermore match the
> > field name.
>
> I was looking at the GPIO API to suggest this name change, but you are right
> we should be consistent with the PWM API here.
> Sorry Florian.

No problem, I agree with the PWM API consistency.

> > > +{
> > > +	return pwm->chip->can_sleep;
> > > +}
> > > +EXPORT_SYMBOL_GPL(pwm_cansleep);
> >
> > Would it make sense to check for NULL pointers here? I guess that
> > passing NULL into the function could be considered a programming error
> > and an oops would be okay, but in that case there's no point in making
> > the function return an int. Also see my next comment.
>
> While it is unlikely to happen it is better to be safe, something like this
> will do:
>
> return pwm ? pwm->chip->can_sleep : 0;

Ok. And what about:

BUG_ON(pwm == NULL);
return pwm->chip->can_sleep;

> > > +
> > >   #ifdef CONFIG_DEBUG_FS
> > >   static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
> > >   {
> > > diff --git a/include/linux/pwm.h b/include/linux/pwm.h
> > > index 70655a2..e2cb5c7 100644
> > > --- a/include/linux/pwm.h
> > > +++ b/include/linux/pwm.h
> > > @@ -146,6 +146,8 @@ struct pwm_ops {
> > >    * @base: number of first PWM controlled by this chip
> > >    * @npwm: number of PWMs controlled by this chip
> > >    * @pwms: array of PWM devices allocated by the framework
> > > + * @can_sleep: flag must be set iff config()/enable()/disable() methods sleep,
> > > + *      as they must while accessing PWM chips over I2C or SPI
> > >    */
> > >   struct pwm_chip {
> > >   	struct device		*dev;
> > > @@ -159,6 +161,7 @@ struct pwm_chip {
> > >   	struct pwm_device *	(*of_xlate)(struct pwm_chip *pc,
> > >   					    const struct of_phandle_args *args);
> > >   	unsigned int		of_pwm_n_cells;
> > > +	unsigned int		can_sleep:1;
> >
> > What's the reason for making this a bitfield? Couldn't we just use a
> > bool instead?
>
> I have also overlooked this. In my version I had the can_sleep as bool also.

Ok for a bool.

Thank you for your reviews. I will send a v3 sometimes today.

Cheers,
Florian
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