Re: [PATCH v4 4/7] pwm: tegra: Parametrize enable register offset

[Uwe Kleine-König]

Hello,

On Tue, Mar 31, 2026 at 11:12:16AM +0900, Mikko Perttunen wrote:
> On Tegra264, the PWM enablement bit is not located at the base address
> of the PWM controller. Hence, introduce an enablement offset field in
> the tegra_pwm_soc structure to describe the offset of the register.
> 
> Co-developed-by: Yi-Wei Wang <yiweiw@xxxxxxxxxx>
> Signed-off-by: Yi-Wei Wang <yiweiw@xxxxxxxxxx>
> Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
> ---
>  drivers/pwm/pwm-tegra.c | 17 ++++++++++++-----
>  1 file changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
> index 358c81cea05b..b925ef914411 100644
> --- a/drivers/pwm/pwm-tegra.c
> +++ b/drivers/pwm/pwm-tegra.c
> @@ -61,6 +61,7 @@
>  
>  struct tegra_pwm_soc {
>  	unsigned int num_channels;
> +	unsigned int enable_reg;
>  };
>  
>  struct tegra_pwm_chip {
> @@ -197,8 +198,9 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  		err = pm_runtime_resume_and_get(pwmchip_parent(chip));
>  		if (err)
>  			return err;
> -	} else
> +	} else if (pc->soc->enable_reg == PWM_CSR_0) {
>  		val |= PWM_ENABLE;
> +	}
>  
>  	pwm_writel(pwm, PWM_CSR_0, val);
>  

The patch is a bit artificial because we don't have a driver yet where
`pc->soc->enable_reg == PWM_CSR_0` doesn't hold. But it looks strange to
me that there is no enable bit set for the pc->soc->enable_reg !=
PWM_CSR_0 case. So I tend to want these changes in squashed into another
patch such that the combined patch handles the enabling completely.

> @@ -213,6 +215,7 @@ static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
>  
>  static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>  {
> +	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
>  	int rc = 0;
>  	u32 val;
>  
> @@ -220,20 +223,22 @@ static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
>  	if (rc)
>  		return rc;
>  
> -	val = pwm_readl(pwm, PWM_CSR_0);
> +

A single empty line is enough.

> +	val = pwm_readl(pwm, pc->soc->enable_reg);
>  	val |= PWM_ENABLE;
> -	pwm_writel(pwm, PWM_CSR_0, val);
> +	pwm_writel(pwm, pc->soc->enable_reg, val);
>  
>  	return 0;
>  }
>  
>  static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
>  {
> +	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
>  	u32 val;
>  
> -	val = pwm_readl(pwm, PWM_CSR_0);
> +	val = pwm_readl(pwm, pc->soc->enable_reg);
>  	val &= ~PWM_ENABLE;
> -	pwm_writel(pwm, PWM_CSR_0, val);
> +	pwm_writel(pwm, pc->soc->enable_reg, val);
>  
>  	pm_runtime_put_sync(pwmchip_parent(chip));
>  }
> @@ -398,10 +403,12 @@ static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
>  
>  static const struct tegra_pwm_soc tegra20_pwm_soc = {
>  	.num_channels = 4,
> +	.enable_reg = PWM_CSR_0,
>  };
>  
>  static const struct tegra_pwm_soc tegra186_pwm_soc = {
>  	.num_channels = 1,
> +	.enable_reg = PWM_CSR_0,
>  };
>  
>  static const struct of_device_id tegra_pwm_of_match[] = {
> 
> -- 
> 2.53.0
>

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