Re: [PATCH] pwm: imx-tpm: keep channel state instead of counting

["Viorel Suman (OSS)" <viorel.suman@oss.nxp.com>]

Hello,

On 26-01-31 00:00:02, Uwe Kleine-König wrote:
> Hello,
> 
> On Fri, Jan 30, 2026 at 04:37:20PM +0200, Viorel Suman (OSS) wrote:
> > diff --git a/drivers/pwm/pwm-imx-tpm.c b/drivers/pwm/pwm-imx-tpm.c
> > index 5b399de16d60..0f8643f4a70b 100644
> > --- a/drivers/pwm/pwm-imx-tpm.c
> > +++ b/drivers/pwm/pwm-imx-tpm.c
> > @@ -62,7 +62,7 @@ struct imx_tpm_pwm_chip {
> >  	void __iomem *base;
> >  	struct mutex lock;
> >  	u32 user_count;
> > -	u32 enable_count;
> > +	u32 enabled_channels;
> >  	u32 real_period;
> >  };
> >  
> > @@ -166,6 +166,10 @@ static int pwm_imx_tpm_get_state(struct pwm_chip *chip,
> >  
> >  	/* get channel status */
> >  	state->enabled = FIELD_GET(PWM_IMX_TPM_CnSC_ELS, val) ? true : false;
> > +	if (state->enabled)
> > +		tpm->enabled_channels |= BIT(pwm->hwpwm);
> > +	else
> > +		tpm->enabled_channels &= ~BIT(pwm->hwpwm);
> 
> I'm not sure about this being the right approach, feels like the driver
> sells the pwm core down the river resulting in something the might work
> now but isn't robust.
> 
> If I understand it right, keeping the enable count balanced depends on
> .get_state() being called.
> 
> The usual and robust approach is that .probe() checks the device state
> and initializes enable counts and the like accordingly.

Thank you for review, I've moved in V2 the device state
check into the probe function as suggested.

>  
> >  	return 0;
> >  }
> > @@ -282,15 +286,19 @@ static int pwm_imx_tpm_apply_hw(struct pwm_chip *chip,
> >  	}
> >  	writel(val, tpm->base + PWM_IMX_TPM_CnSC(pwm->hwpwm));
> >  
> > -	/* control the counter status */
> > +	/* control the channel state */
> >  	if (state->enabled != c.enabled) {
> >  		val = readl(tpm->base + PWM_IMX_TPM_SC);
> >  		if (state->enabled) {
> > -			if (++tpm->enable_count == 1)
> > +			if (tpm->enabled_channels == 0) {
> >  				val |= PWM_IMX_TPM_SC_CMOD_INC_EVERY_CLK;
> > +			}
> 
> No { } for one line blocks please.

Fixed in V2.

> 
> > +			tpm->enabled_channels |= BIT(pwm->hwpwm);
> >  		} else {
> > -			if (--tpm->enable_count == 0)
> > +			tpm->enabled_channels &= ~BIT(pwm->hwpwm);
> > +			if (tpm->enabled_channels == 0) {
> >  				val &= ~PWM_IMX_TPM_SC_CMOD;
> > +			}
> >  		}
> >  		writel(val, tpm->base + PWM_IMX_TPM_SC);
> >  	}
> 
> Best regards
> Uwe

Best regards,
Vorel