On Mon, Oct 06, 2014 at 08:35:28PM -0700, Stephen Warren wrote: > On 10/02/2014 04:41 AM, Bart Tanghe wrote: > > Add pwm driver for Broadcom BCM2835 processor (Raspberry Pi) > > > > Signed-off-by: Bart Tanghe <bart.tan...@thomasmore.be> > > --- > > Changes in v5: > > By v5, I would drop "rfc" from the email subject.
And resend as well. Use resend only if you're resending without having
made any changes.
> > diff --git a/drivers/pwm/pwm-bcm2835.c b/drivers/pwm/pwm-bcm2835.c
>
> > +static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device
> > *pwm)
> > +{
> > + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> > + u32 value;
> > +
> > + value = readl(pc->base);
> > + value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_STRIDE * pwm->pwm);
> > + value |= (PWM_MODE << (PWM_CONTROL_STRIDE * pwm->pwm));
> > + writel(value, pc->base);
> > + return 0;
> > +}
> > +
> > +static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> > +{
> > + struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
> > + u32 value;
> > +
> > + value = readl(pc->base)
> > + value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_STRIDE * pwm->pwm);
> > + value &= (~DEFAULT << (PWM_CONTROL_STRIDE * pwm->pwm));
>
> What is this second mask operation intended to do? The first mask
> operation already clears all the control bits, so clearing them again
> doesn't seem useful.
I suspend that you'll also want to use pwm->hwpwm instead of pwm->pwm.
pwm->hwpwm is the index of the PWM for the chip, whereas pwm->pwm is a
global index so the above breaks if another driver registered a PWM chip
before this driver.
Thierry
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