linux-kernel - Re: [PATCH 5/9] pwm: stm32: add support for stm32mp25

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Message-ID: <lptm6gh2lzjqxm26lbmdw4yr2fowo6ytxwzqwl65khrx5xpcox@u25yzz6ssdy5>
Date: Wed, 18 Dec 2024 11:05:03 +0100
From: Uwe Kleine-König <ukleinek@...nel.org>
To: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Cc: lee@...nel.org, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, alexandre.torgue@...s.st.com, wbg@...nel.org, jic23@...nel.org, 
	catalin.marinas@....com, will@...nel.org, devicetree@...r.kernel.org, 
	linux-stm32@...md-mailman.stormreply.com, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org, linux-pwm@...r.kernel.org, 
	olivier.moysan@...s.st.com
Subject: Re: [PATCH 5/9] pwm: stm32: add support for stm32mp25

On Wed, Dec 18, 2024 at 10:01:49AM +0100, Fabrice Gasnier wrote:
> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
> index 17e591f61efb..99383e09920e 100644
> --- a/drivers/pwm/pwm-stm32.c
> +++ b/drivers/pwm/pwm-stm32.c
> @@ -19,6 +19,7 @@
>  #define CCMR_CHANNEL_SHIFT 8
>  #define CCMR_CHANNEL_MASK  0xFF
>  #define MAX_BREAKINPUT 2
> +#define MAX_PWM_OUTPUT 4

I would prefer a less generic name. Something like STM32_PWM_MAX_OUTPUT.
 
>  struct stm32_breakinput {
>  	u32 index;
> [...]
> @@ -790,11 +800,31 @@ static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
>  	priv->have_complementary_output = (ccer != 0);
>  }
>  
> -static unsigned int stm32_pwm_detect_channels(struct regmap *regmap,
> +static unsigned int stm32_pwm_detect_channels(struct stm32_timers *ddata,
>  					      unsigned int *num_enabled)
>  {
> +	struct regmap *regmap = ddata->regmap;
>  	u32 ccer, ccer_backup;
>  
> +	if (ddata->ipidr) {
> +		unsigned int npwm = 0;

No need to initialize npwm.

> +		u32 val;
> +
> +		/* Simply deduce from HWCFGR the number of outputs (MP25). */
> +		regmap_read(regmap, TIM_HWCFGR1, &val);
> +
> +		/*
> +		 * Timers may have more capture/compare channels than the
> +		 * actual number of PWM channel outputs (e.g. TIM_CH[1..4]).
> +		 */
> +		npwm = FIELD_GET(TIM_HWCFGR1_NB_OF_CC, val);
> +
> +		regmap_read(regmap, TIM_CCER, &ccer);
> +		*num_enabled = hweight32(ccer & TIM_CCER_CCXE);

So the part that determines *num_enabled is the same for both variants.
Maybe it's possible to share the code for that?

> +		return npwm < MAX_PWM_OUTPUT ? npwm : MAX_PWM_OUTPUT;
> +	}
> +
>  	/*
>  	 * If channels enable bits don't exist writing 1 will have no
>  	 * effect so we can detect and count them.

Best regards
Uwe

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