linux-kernel - Re: [PATCH v18] pwm: airoha: Add support for EN7581 SoC

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Message-ID: <aF5dHDr8yDSKlp5j@smile.fi.intel.com>
Date: Fri, 27 Jun 2025 11:58:04 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Christian Marangi <ansuelsmth@...il.com>
Cc: Uwe Kleine-König <ukleinek@...nel.org>,
	linux-kernel@...r.kernel.org, linux-pwm@...r.kernel.org,
	Benjamin Larsson <benjamin.larsson@...exis.eu>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Lorenzo Bianconi <lorenzo@...nel.org>
Subject: Re: [PATCH v18] pwm: airoha: Add support for EN7581 SoC

On Fri, Jun 27, 2025 at 12:47:53AM +0200, Christian Marangi wrote:
> From: Benjamin Larsson <benjamin.larsson@...exis.eu>
> 
> Introduce driver for PWM module available on EN7581 SoC.

...

> + * Copyright 2025 Markus Gothe <markus.gothe@...exis.eu>
> + *		  Christian Marangi <ansuelsmth@...il.com>

I'm not sure you can change the copyright line like this. I would rather expect

 * Copyright 2012 Markus Gothe <markus.gothe@...exis.eu>
 * Copyright 2025 Christian Marangi <ansuelsmth@...il.com>

(Sorry, I forgot the exact original year there, but you got the point)

...

> +	/* Global mutex to protect bucket used refcount_t */
> +	struct mutex mutex;

This makes a little sense. Either you use refcount_t (which is atomic) or
use mutex + regular variable.

...

> +	/*
> +	 * It is necessary to explicitly shift out all zeros after muxing
> +	 * to initialize the shift register before enabling PWM
> +	 * mode because in PWM mode SIPO will not start shifting until
> +	 * it needs to output a non-zero value (bit 31 of led_data
> +	 * indicates shifting in progress and it must return to zero
> +	 * before led_data can be written or PWM mode can be set)

Missing period at the end.

> +	 */

...

> +static void airoha_pwm_disable(struct airoha_pwm *pc, struct pwm_device *pwm)
> +{
> +	/* Disable PWM and release the bucket */
> +	airoha_pwm_config_flash_map(pc, pwm->hwpwm, -1);
> +	airoha_pwm_release_bucket_config(pc, pwm->hwpwm);
> +
> +	clear_bit(pwm->hwpwm, pc->initialized);
> +
> +	/* If no SIPO is used, disable the shift register chip */
> +	if (find_next_bit(pc->initialized, AIROHA_PWM_MAX_CHANNELS,
> +			  AIROHA_PWM_NUM_GPIO) >= AIROHA_PWM_NUM_GPIO)

This can be rewritten as

	if (!bitmap_read(pc->initialized, AIROHA_PWM_NUM_GPIO, AIROHA_PWM_NUM_SIPO))

(seems to me that the above code is buggy and has to have a check against the
 full size of bitmap).

> +		regmap_clear_bits(pc->regmap, AIROHA_PWM_REG_SIPO_FLASH_MODE_CFG,
> +				  AIROHA_PWM_SERIAL_GPIO_FLASH_MODE);
> +}

-- 
With Best Regards,
Andy Shevchenko