On Wed, Apr 07, 2021 at 08:16:19AM +0200, Uwe Kleine-König wrote:
> On Tue, Apr 06, 2021 at 06:41:40PM +0200, Clemens Gruber wrote:
> > Regmap operations can fail if the underlying subsystem is not working
> > properly (e.g. hogged I2C bus, etc.)
> > As this is useful information for the user, print an error message if it
> > happens.
> > Let probe fail if the first regmap_read or the first regmap_write fails.
> >
> > Signed-off-by: Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>
> > ---
> > Changes since v6:
> > - Rebased
> >
> > drivers/pwm/pwm-pca9685.c | 83 ++++++++++++++++++++++++++++-----------
> > 1 file changed, 59 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
> > index cf0c98e4ef44..8a4993882b40 100644
> > --- a/drivers/pwm/pwm-pca9685.c
> > +++ b/drivers/pwm/pwm-pca9685.c
> > @@ -107,6 +107,30 @@ static bool pca9685_prescaler_can_change(struct pca9685 *pca, int channel)
> > return test_bit(channel, pca->pwms_enabled);
> > }
> >
> > +static int pca9685_read_reg(struct pca9685 *pca, unsigned int reg, unsigned int *val)
> > +{
> > + struct device *dev = pca->chip.dev;
> > + int err;
> > +
> > + err = regmap_read(pca->regmap, reg, val);
> > + if (err != 0)
> > + dev_err(dev, "regmap_read of register 0x%x failed: %d\n", reg, err);
>
> Please use %pe to emit the error code instead of %d.
Will do.
>
> > +
> > + return err;
> > +}
> > +
> > +static int pca9685_write_reg(struct pca9685 *pca, unsigned int reg, unsigned int val)
> > +{
> > + struct device *dev = pca->chip.dev;
> > + int err;
> > +
> > + err = regmap_write(pca->regmap, reg, val);
> > + if (err != 0)
> > + dev_err(dev, "regmap_write to register 0x%x failed: %d\n", reg, err);
> > +
> > + return err;
> > +}
> > +
> > /* Helper function to set the duty cycle ratio to duty/4096 (e.g. duty=2048 -> 50%) */
> > static void pca9685_pwm_set_duty(struct pca9685 *pca, int channel, unsigned int duty)
> > {
> > @@ -115,12 +139,12 @@ static void pca9685_pwm_set_duty(struct pca9685 *pca, int channel, unsigned int
> >
> > if (duty == 0) {
> > /* Set the full OFF bit, which has the highest precedence */
> > - regmap_write(pca->regmap, REG_OFF_H(channel), LED_FULL);
> > + pca9685_write_reg(pca, REG_OFF_H(channel), LED_FULL);
>
> You didn't check all return codes? How did you select the calls to
> check?
No, because it would become a big mess and really obstruct readability
in my opinion.
So I chose some kind of middleground:
I decided to check the first regmap_read and regmap_write in probe and
return the error code if something goes wrong there.
If something goes wrong after probe, I only print an error message.
Is that acceptable?
Thanks,
Clemens
