| Message ID | 20200717182512.26001-1-scott.branden@broadcom.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [v2] pwm: bcm-iproc: handle clk_get_rate() return | expand |
On 7/17/2020 11:25 AM, Scott Branden wrote: > From: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> > > Handle clk_get_rate() returning <= 0 condition to avoid > possible division by zero. > > Fixes: daa5abc41c80 ("pwm: Add support for Broadcom iProc PWM controller") > Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> > Signed-off-by: Scott Branden <scott.branden@broadcom.com> > > --- > Changes from v1: ensure 'polarity' and 'enabled' are populated > when clk_get_rate is 0. > --- > drivers/pwm/pwm-bcm-iproc.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c > index 1f829edd8ee7..d392a828fc49 100644 > --- a/drivers/pwm/pwm-bcm-iproc.c > +++ b/drivers/pwm/pwm-bcm-iproc.c > @@ -85,8 +85,6 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > u64 tmp, multi, rate; > u32 value, prescale; > > - rate = clk_get_rate(ip->clk); > - > value = readl(ip->base + IPROC_PWM_CTRL_OFFSET); > > if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm))) > @@ -99,6 +97,13 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > else > state->polarity = PWM_POLARITY_INVERSED; > > + rate = clk_get_rate(ip->clk); > + if (rate == 0) { > + state->period = 0; > + state->duty_cycle = 0; > + return; > + } > + > value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET); > prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm); > prescale &= IPROC_PWM_PRESCALE_MAX; > This patch looks good to me. Thanks! Reviewed-by: Ray Jui <ray.jui@broadcom.com>
On Fri, Jul 17, 2020 at 11:25:12AM -0700, Scott Branden wrote: > From: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> > > Handle clk_get_rate() returning <= 0 condition to avoid > possible division by zero. You advertise handling <= 0, but in the code only == 0 is checked. One of the two is wrong ... Best regards Uwe
On 2020-07-17 4:04 p.m., Uwe Kleine-König wrote: > On Fri, Jul 17, 2020 at 11:25:12AM -0700, Scott Branden wrote: >> From: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com> >> >> Handle clk_get_rate() returning <= 0 condition to avoid >> possible division by zero. > You advertise handling <= 0, but in the code only == 0 is checked. One > of the two is wrong ... I checked - clk_get_rate can't return negative values. I'll update the commit message from <= to ==. > > Best regards > Uwe > Thanks, Scott
diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c index 1f829edd8ee7..d392a828fc49 100644 --- a/drivers/pwm/pwm-bcm-iproc.c +++ b/drivers/pwm/pwm-bcm-iproc.c @@ -85,8 +85,6 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm, u64 tmp, multi, rate; u32 value, prescale; - rate = clk_get_rate(ip->clk); - value = readl(ip->base + IPROC_PWM_CTRL_OFFSET); if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm))) @@ -99,6 +97,13 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm, else state->polarity = PWM_POLARITY_INVERSED; + rate = clk_get_rate(ip->clk); + if (rate == 0) { + state->period = 0; + state->duty_cycle = 0; + return; + } + value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET); prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm); prescale &= IPROC_PWM_PRESCALE_MAX;