Messages in this thread | | | Date | Mon, 23 Mar 2020 09:25:40 +0100 | From | Uwe Kleine-König <> | Subject | Re: [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return |
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On Mon, Mar 23, 2020 at 12:23:17PM +0530, Rayagonda Kokatanur wrote: > Handle clk_get_rate() returning <= 0 condition to avoid > possible division by zero.
Was this noticed during a review and is more theoretic. Or does this (depending on pre-boot state) result in a kernel crash?
> Fixes: daa5abc41c80 ("pwm: Add support for Broadcom iProc PWM controller") > Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> > --- > drivers/pwm/pwm-bcm-iproc.c | 32 +++++++++++++++++++------------- > 1 file changed, 19 insertions(+), 13 deletions(-) > > diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c > index 1f829edd8ee7..8bbd2a04fead 100644 > --- a/drivers/pwm/pwm-bcm-iproc.c > +++ b/drivers/pwm/pwm-bcm-iproc.c > @@ -99,19 +99,25 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > else > state->polarity = PWM_POLARITY_INVERSED; > > - value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET); > - prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm); > - prescale &= IPROC_PWM_PRESCALE_MAX; > - > - multi = NSEC_PER_SEC * (prescale + 1); > - > - value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm)); > - tmp = (value & IPROC_PWM_PERIOD_MAX) * multi; > - state->period = div64_u64(tmp, rate); > - > - value = readl(ip->base + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm)); > - tmp = (value & IPROC_PWM_PERIOD_MAX) * multi; > - state->duty_cycle = div64_u64(tmp, rate); > + if (rate == 0) { > + state->period = 0; > + state->duty_cycle = 0; > + } else { > + value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET); > + prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm); > + prescale &= IPROC_PWM_PRESCALE_MAX; > + > + multi = NSEC_PER_SEC * (prescale + 1); > + > + value = readl(ip->base + IPROC_PWM_PERIOD_OFFSET(pwm->hwpwm)); > + tmp = (value & IPROC_PWM_PERIOD_MAX) * multi; > + state->period = div64_u64(tmp, rate); > + > + value = readl(ip->base + > + IPROC_PWM_DUTY_CYCLE_OFFSET(pwm->hwpwm)); > + tmp = (value & IPROC_PWM_PERIOD_MAX) * multi; > + state->duty_cycle = div64_u64(tmp, rate); > + }
The change looks fine.
Best regards Uwe
-- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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