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* [PATCH v1 0/2] Handle return value and remove unnecessary check
@ 2020-03-23  6:53 Rayagonda Kokatanur
  2020-03-23  6:53 ` [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return Rayagonda Kokatanur
  2020-03-23  6:53 ` [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty' Rayagonda Kokatanur
  0 siblings, 2 replies; 7+ messages in thread
From: Rayagonda Kokatanur @ 2020-03-23  6:53 UTC (permalink / raw)
  To: Thierry Reding, Uwe Kleine-König, Ray Jui, Scott Branden,
	bcm-kernel-feedback-list, Yendapally Reddy Dhananjaya Reddy,
	linux-pwm, linux-arm-kernel, linux-kernel
  Cc: Rayagonda Kokatanur

This patch series contains following changes,
1. Handle clk_get_rate() return
2. remove unnecessary check of 'duty'

Rayagonda Kokatanur (2):
  pwm: bcm-iproc: handle clk_get_rate() return
  pwm: bcm-iproc: remove unnecessary check of 'duty'

 drivers/pwm/pwm-bcm-iproc.c | 35 ++++++++++++++++++++---------------
 1 file changed, 20 insertions(+), 15 deletions(-)

-- 
2.17.1


^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return
  2020-03-23  6:53 [PATCH v1 0/2] Handle return value and remove unnecessary check Rayagonda Kokatanur
@ 2020-03-23  6:53 ` Rayagonda Kokatanur
  2020-03-23  8:25   ` Uwe Kleine-König
  2020-03-23  6:53 ` [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty' Rayagonda Kokatanur
  1 sibling, 1 reply; 7+ messages in thread
From: Rayagonda Kokatanur @ 2020-03-23  6:53 UTC (permalink / raw)
  To: Thierry Reding, Uwe Kleine-König, Ray Jui, Scott Branden,
	bcm-kernel-feedback-list, Yendapally Reddy Dhananjaya Reddy,
	linux-pwm, linux-arm-kernel, linux-kernel
  Cc: Rayagonda Kokatanur

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>
---
 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);
+	}
 }
 
 static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty'
  2020-03-23  6:53 [PATCH v1 0/2] Handle return value and remove unnecessary check Rayagonda Kokatanur
  2020-03-23  6:53 ` [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return Rayagonda Kokatanur
@ 2020-03-23  6:53 ` Rayagonda Kokatanur
  2020-03-23  8:28   ` Uwe Kleine-König
  1 sibling, 1 reply; 7+ messages in thread
From: Rayagonda Kokatanur @ 2020-03-23  6:53 UTC (permalink / raw)
  To: Thierry Reding, Uwe Kleine-König, Ray Jui, Scott Branden,
	bcm-kernel-feedback-list, Yendapally Reddy Dhananjaya Reddy,
	linux-pwm, linux-arm-kernel, linux-kernel
  Cc: Rayagonda Kokatanur

Variable 'duty' is u32. Hence the less-than zero
comparison is never true, remove the check.

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 | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
index 8bbd2a04fead..1bb66721f985 100644
--- a/drivers/pwm/pwm-bcm-iproc.c
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -149,8 +149,7 @@ static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		value = rate * state->duty_cycle;
 		duty = div64_u64(value, div);
 
-		if (period < IPROC_PWM_PERIOD_MIN ||
-		    duty < IPROC_PWM_DUTY_CYCLE_MIN)
+		if (period < IPROC_PWM_PERIOD_MIN)
 			return -EINVAL;
 
 		if (period <= IPROC_PWM_PERIOD_MAX &&
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* Re: [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return
  2020-03-23  6:53 ` [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return Rayagonda Kokatanur
@ 2020-03-23  8:25   ` Uwe Kleine-König
  2020-03-23  9:05     ` Rayagonda Kokatanur
  0 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2020-03-23  8:25 UTC (permalink / raw)
  To: Rayagonda Kokatanur
  Cc: Thierry Reding, Ray Jui, Scott Branden, bcm-kernel-feedback-list,
	Yendapally Reddy Dhananjaya Reddy, linux-pwm, linux-arm-kernel,
	linux-kernel

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/ |

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty'
  2020-03-23  6:53 ` [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty' Rayagonda Kokatanur
@ 2020-03-23  8:28   ` Uwe Kleine-König
  2020-03-23  9:13     ` Rayagonda Kokatanur
  0 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2020-03-23  8:28 UTC (permalink / raw)
  To: Rayagonda Kokatanur
  Cc: Thierry Reding, Ray Jui, Scott Branden, bcm-kernel-feedback-list,
	Yendapally Reddy Dhananjaya Reddy, linux-pwm, linux-arm-kernel,
	linux-kernel

On Mon, Mar 23, 2020 at 12:23:18PM +0530, Rayagonda Kokatanur wrote:
> Variable 'duty' is u32. Hence the less-than zero
> comparison is never true, remove the check.

How did you find that one? I assume it was a compiler warning you fixed
here? In this case quoting the warning improves the commit log.

Also the commit log suggests that IPROC_PWM_DUTY_CYCLE_MIN is zero.
Maybe mentioning that explicitly is a nice addition, too.

> 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 | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> index 8bbd2a04fead..1bb66721f985 100644
> --- a/drivers/pwm/pwm-bcm-iproc.c
> +++ b/drivers/pwm/pwm-bcm-iproc.c
> @@ -149,8 +149,7 @@ static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  		value = rate * state->duty_cycle;
>  		duty = div64_u64(value, div);
>  
> -		if (period < IPROC_PWM_PERIOD_MIN ||
> -		    duty < IPROC_PWM_DUTY_CYCLE_MIN)
> +		if (period < IPROC_PWM_PERIOD_MIN)
>  			return -EINVAL;

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return
  2020-03-23  8:25   ` Uwe Kleine-König
@ 2020-03-23  9:05     ` Rayagonda Kokatanur
  0 siblings, 0 replies; 7+ messages in thread
From: Rayagonda Kokatanur @ 2020-03-23  9:05 UTC (permalink / raw)
  To: Uwe Kleine-König
  Cc: Thierry Reding, Ray Jui, Scott Branden, BCM Kernel Feedback,
	Yendapally Reddy Dhananjaya Reddy, linux-pwm, linux-arm-kernel,
	Linux Kernel Mailing List

On Mon, Mar 23, 2020 at 1:55 PM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> 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?

This is reported by internal coverity tool.
>
> > 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/ |

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty'
  2020-03-23  8:28   ` Uwe Kleine-König
@ 2020-03-23  9:13     ` Rayagonda Kokatanur
  0 siblings, 0 replies; 7+ messages in thread
From: Rayagonda Kokatanur @ 2020-03-23  9:13 UTC (permalink / raw)
  To: Uwe Kleine-König
  Cc: Thierry Reding, Ray Jui, Scott Branden, BCM Kernel Feedback,
	Yendapally Reddy Dhananjaya Reddy, linux-pwm, linux-arm-kernel,
	Linux Kernel Mailing List

On Mon, Mar 23, 2020 at 1:58 PM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
>
> On Mon, Mar 23, 2020 at 12:23:18PM +0530, Rayagonda Kokatanur wrote:
> > Variable 'duty' is u32. Hence the less-than zero
> > comparison is never true, remove the check.
>
> How did you find that one? I assume it was a compiler warning you fixed
> here? In this case quoting the warning improves the commit log.
Its reported by internal coverity tool.
>
> Also the commit log suggests that IPROC_PWM_DUTY_CYCLE_MIN is zero.
> Maybe mentioning that explicitly is a nice addition, too.
Okay, will add this to commit message. Thanks.
>
> > 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 | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> > index 8bbd2a04fead..1bb66721f985 100644
> > --- a/drivers/pwm/pwm-bcm-iproc.c
> > +++ b/drivers/pwm/pwm-bcm-iproc.c
> > @@ -149,8 +149,7 @@ static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> >               value = rate * state->duty_cycle;
> >               duty = div64_u64(value, div);
> >
> > -             if (period < IPROC_PWM_PERIOD_MIN ||
> > -                 duty < IPROC_PWM_DUTY_CYCLE_MIN)
> > +             if (period < IPROC_PWM_PERIOD_MIN)
> >                       return -EINVAL;
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |

^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2020-03-23  9:14 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-03-23  6:53 [PATCH v1 0/2] Handle return value and remove unnecessary check Rayagonda Kokatanur
2020-03-23  6:53 ` [PATCH v1 1/2] pwm: bcm-iproc: handle clk_get_rate() return Rayagonda Kokatanur
2020-03-23  8:25   ` Uwe Kleine-König
2020-03-23  9:05     ` Rayagonda Kokatanur
2020-03-23  6:53 ` [PATCH v1 2/2] pwm: bcm-iproc: remove unnecessary check of 'duty' Rayagonda Kokatanur
2020-03-23  8:28   ` Uwe Kleine-König
2020-03-23  9:13     ` Rayagonda Kokatanur

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