Messages in this thread | | | Date | Sat, 30 May 2015 09:42:38 -0700 | Subject | Re: [PATCH v8 4/5] pwm: kona: Add debug info to config function | From | Tim Kryger <> |
| |
On Tue, May 26, 2015 at 1:08 PM, Jonathan Richardson <jonathar@broadcom.com> wrote: > Adds debugging info to config function where duty cycle and period > are calculated and verified. > > Signed-off-by: Jonathan Richardson <jonathar@broadcom.com> > --- > drivers/pwm/pwm-bcm-kona.c | 25 +++++++++++++++++++++++-- > 1 file changed, 23 insertions(+), 2 deletions(-) > > diff --git a/drivers/pwm/pwm-bcm-kona.c b/drivers/pwm/pwm-bcm-kona.c > index c87621f..0ddf19b 100644 > --- a/drivers/pwm/pwm-bcm-kona.c > +++ b/drivers/pwm/pwm-bcm-kona.c > @@ -138,18 +138,39 @@ static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm, > dc = div64_u64(val, div); > > /* If duty_ns or period_ns are not achievable then return */ > - if (pc < PERIOD_COUNT_MIN || dc < DUTY_CYCLE_HIGH_MIN)
The original code was based on the SPEAr PWM driver which has a non-zero PWMDCR_MIN_DUTY such that the second condition here can evaluate to true.
This isn't the case for the Kona PWM where DUTY_CYCLE_HIGH_MIN is zero.
> + if (pc < PERIOD_COUNT_MIN) { > + dev_warn(chip->dev, > + "%s: pwm[%d]: period=%d is not achievable, pc=%lu, prescale=%lu\n", > + __func__, chan, period_ns, pc, prescale); > return -EINVAL; > + }
Why not just print the minimum allowable period with the provided clock?
I don't think pc and prescale will be particularly helpful to users.
Also, do we really need to print __func__ here?
> + > + if (dc < DUTY_CYCLE_HIGH_MIN) { > + if (0 != duty_ns) { > + dev_warn(chip->dev, > + "%s: pwm[%d]: duty cycle=%d is not achievable, dc=%lu, prescale=%lu\n", > + __func__, chan, duty_ns, dc, prescale); > + } > + return -EINVAL; > + }
The above block is unreachable code.
> > /* If pc and dc are in bounds, the calculation is done */ > if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX) > break; > > /* Otherwise, increase prescale and recalculate pc and dc */ > - if (++prescale > PRESCALE_MAX) > + if (++prescale > PRESCALE_MAX) { > + dev_warn(chip->dev, > + "%s: pwm[%d]: Prescale (=%lu) within max (=%d) for period=%d and duty cycle=%d is not achievable\n", > + __func__, chan, prescale, PRESCALE_MAX, > + period_ns, duty_ns); > return -EINVAL; > + } > }
The user got here because they specified a period larger than the maximum supported so why not tell them largest value that can be supported instead of confusing them with prescale and PRESCALE_MAX?
> > + dev_dbg(chip->dev, "pwm[%d]: period=%lu, duty_high=%lu, prescale=%lu\n", > + chan, pc, dc, prescale); > +
This could be more clear. It prints pc but calls it period.
> /* > * Don't apply settings if disabled. The period and duty cycle are > * always calculated above to ensure the new values are > -- > 1.7.9.5 >
| |