Re: [PATCH] pwm: bcm-iproc: handle clk_get_rate() return

[Scott Branden]

On 2020-07-17 10:22 a.m., Ray Jui wrote:


On 7/17/2020 10:07 AM, Scott Branden wrote:

From: 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 
Signed-off-by: Scott Branden 
---
  drivers/pwm/pwm-bcm-iproc.c | 5 +
  1 file changed, 5 insertions(+)

diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
index 1f829edd8ee7..72a8607b6c8d 100644
--- a/drivers/pwm/pwm-bcm-iproc.c
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -86,6 +86,11 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, 
struct pwm_device *pwm,
u32 value, prescale;
  
  	rate = clk_get_rate(ip->clk);

+   if (rate == 0) {
+   state->period = 0;
+   state->duty_cycle = 0;
+   return;
+   }

I'll move the logic after the polarity and enabled fields are populated.

Based on the pwm core code, 'get_state' expects the following fields to
be populated: 'polarity', 'enabled', 'period', and 'duty cycle'.

The above logic will leave 'polarity' and 'enabled' completely
unpopulated when clock rate is zero.

  
  	value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
  

Re: [PATCH] pwm: bcm-iproc: handle clk_get_rate() return

[Ray Jui]

On 7/17/2020 10:07 AM, Scott Branden wrote:
> From: 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 
> Signed-off-by: Scott Branden 
> ---
>  drivers/pwm/pwm-bcm-iproc.c | 5 +
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> index 1f829edd8ee7..72a8607b6c8d 100644
> --- a/drivers/pwm/pwm-bcm-iproc.c
> +++ b/drivers/pwm/pwm-bcm-iproc.c
> @@ -86,6 +86,11 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, 
> struct pwm_device *pwm,
>   u32 value, prescale;
>  
>   rate = clk_get_rate(ip->clk);
> + if (rate == 0) {
> + state->period = 0;
> + state->duty_cycle = 0;
> + return;
> + }

Based on the pwm core code, 'get_state' expects the following fields to
be populated: 'polarity', 'enabled', 'period', and 'duty cycle'.

The above logic will leave 'polarity' and 'enabled' completely
unpopulated when clock rate is zero.

>  
>   value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
>  
> 

[PATCH] pwm: bcm-iproc: handle clk_get_rate() return

[Scott Branden]

From: 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 
Signed-off-by: Scott Branden 
---
 drivers/pwm/pwm-bcm-iproc.c | 5 +
 1 file changed, 5 insertions(+)

diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
index 1f829edd8ee7..72a8607b6c8d 100644
--- a/drivers/pwm/pwm-bcm-iproc.c
+++ b/drivers/pwm/pwm-bcm-iproc.c
@@ -86,6 +86,11 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, 
struct pwm_device *pwm,
u32 value, prescale;
 
rate = clk_get_rate(ip->clk);
+   if (rate == 0) {
+   state->period = 0;
+   state->duty_cycle = 0;
+   return;
+   }
 
value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
 
-- 
2.17.1