On Wed, Oct 09, 2019 at 11:51:05AM +0200, Fabrice Gasnier wrote: > On 10/8/19 4:45 PM, Uwe Kleine-König 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 [1]. > >> > >> [1] https://lkml.org/lkml/2019/10/1/207 > >> > >> Signed-off-by: Fabrice Gasnier <fabrice.gasn...@st.com> > >> --- > >> 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. > > Hi Uwe, > > 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. > */
I still fail to understand. This is an input that determines the actual value of the output pin? What makes a shutdown of outputs safe? What is a shutdown anyhow? Apart from that: s/do not make probe failed/don't fail to probe/. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
