Re: [PATCH] pwm: stm32: add comment to better describe breakinput feature
From: Fabrice Gasnier
Date: Wed Oct 09 2019 - 05:51:19 EST
On 10/8/19 4:45 PM, Uwe Kleine-KÃnig wrote:
> On Tue, Oct 08, 2019 at 01:41:27PM +0200, Fabrice Gasnier wrote:
>> Add a comment to better describe the purpose of breakinput feature that
>> can be found on some STM32 timer instances. Briefly comment on the
>> characteristics of this input for PWM, and pinmuxing as suggested in .
>>  https://lkml.org/lkml/2019/10/1/207
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
>> drivers/pwm/pwm-stm32.c | 8 +++++++-
>> 1 file changed, 7 insertions(+), 1 deletion(-)
>> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
>> index 359b085..6406ebb 100644
>> --- a/drivers/pwm/pwm-stm32.c
>> +++ b/drivers/pwm/pwm-stm32.c
>> @@ -522,8 +522,14 @@ static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
>> sizeof(struct stm32_breakinput));
>> + * Some timer instances can have BRK input pins (e.g. basically a fault
>> + * pin from the output power stage). The break feature allows a safe
>> + * shut-down of the PWM outputs to a predefined state. Further details
>> + * are available in application note AN4277, "Using STM32 device PWM
>> + * shut-down features..."
> Without having read the application note I don't understand the purpose.
> Not sure if this should be a show stopper though.
I can rephrase this. Do you think the bellow comment would be more
relevant and easy to understand ?
* The break feature allows a safe shut-down of the PWM outputs.
* It's based on the BRK event signal defined in the dt-bindings
* by <index level filter> values.
* Because "st,breakinput" parameter is optional do not make probe
* failed if it doesn't exist.
>> * Because "st,breakinput" parameter is optional do not make probe
>> - * failed if it doesn't exist.
>> + * failed if it doesn't exist. The pinctrl handle must hold the BRK
>> + * pin(s) when using "st,breakinput" property.
> Is this a comment that has a better place in the binding doc?
You're right, this is unneeded here. I'll remove this.
> Best regards