linux-kernel - Re: [PATCH 1/3] leds: pca9532: Use PWM1 for hardware blinking

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Message-ID: <20240531145523.GN1005600@google.com>
Date: Fri, 31 May 2024 15:55:23 +0100
From: Lee Jones <lee@...nel.org>
To: Bastien Curutchet <bastien.curutchet@...tlin.com>
Cc: Riku Voipio <riku.voipio@....fi>, Pavel Machek <pavel@....cz>,
	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	herve.codina@...tlin.com, christophercordahi@...ometrics.ca
Subject: Re: [PATCH 1/3] leds: pca9532: Use PWM1 for hardware blinking

On Mon, 27 May 2024, Bastien Curutchet wrote:

> PSC0/PWM0 are used by all leds for brightness and blinking. This causes

LEDs everywhere please.

> conflicts when you set a brightness of a new led while an other one is
> already using PWM0 for blinking.
> 
> Use PSC1/PWM1 for blinking.
> Check that no other led is already blinking with a different PSC1/PWM1
> configuration to avoid conflict.
> 
> Signed-off-by: Bastien Curutchet <bastien.curutchet@...tlin.com>
> ---
>  drivers/leds/leds-pca9532.c | 49 ++++++++++++++++++++++++++++++-------
>  1 file changed, 40 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/leds/leds-pca9532.c b/drivers/leds/leds-pca9532.c
> index bf8bb8fc007c..c210608ad336 100644
> --- a/drivers/leds/leds-pca9532.c
> +++ b/drivers/leds/leds-pca9532.c
> @@ -191,29 +191,60 @@ static int pca9532_set_brightness(struct led_classdev *led_cdev,
>  	return err;
>  }
>  
> +static int pca9532_update_hw_blink(struct pca9532_led *led,
> +				   unsigned long delay_on, unsigned long delay_off)
> +{
> +	struct pca9532_data *data = i2c_get_clientdata(led->client);
> +	unsigned int psc;
> +	int i;
> +
> +	/* Look for others leds that already use PWM1 */
> +	for (i = 0; i < data->chip_info->num_leds; i++) {
> +		struct pca9532_led *other = &data->leds[i];
> +
> +		if (other == led)
> +			continue;

Don't bunch things up please - new line here.

> +		if (other->state == PCA9532_PWM1) {
> +			if (other->ldev.blink_delay_on != delay_on ||
> +			    other->ldev.blink_delay_off != delay_off) {
> +				dev_dbg(&led->client->dev,
> +					"HW can handle only one blink configuration at a time\n");
> +				return -EINVAL;
> +			}
> +		}
> +	}
> +
> +	psc = ((delay_on + delay_off) * 152 - 1) / 1000;

What are these funny magic numbers?  Define them please.

> +	if (psc > 255) {

And this.

> +		dev_dbg(&led->client->dev, "Blink period too long to be handled by hardware\n");

If you're returning an error, this should be dev_err().

> +		return -EINVAL;
> +	}
> +
> +	data->psc[1] = psc;

Can we define these indexes please?

> +	data->pwm[1] = (delay_on * 255) / (delay_on + delay_off);
> +
> +	return pca9532_setpwm(data->client, 1);
> +}
> +
>  static int pca9532_set_blink(struct led_classdev *led_cdev,
>  	unsigned long *delay_on, unsigned long *delay_off)
>  {
>  	struct pca9532_led *led = ldev_to_led(led_cdev);
>  	struct i2c_client *client = led->client;
> -	int psc;
> -	int err = 0;
> +	struct pca9532_data *data = i2c_get_clientdata(client);

Did you build this with W=1?  This looks unused.

> +	int err;
>  
>  	if (*delay_on == 0 && *delay_off == 0) {
>  		/* led subsystem ask us for a blink rate */
>  		*delay_on = 1000;
>  		*delay_off = 1000;
>  	}
> -	if (*delay_on != *delay_off || *delay_on > 1690 || *delay_on < 6)
> -		return -EINVAL;
>  
> -	/* Thecus specific: only use PSC/PWM 0 */
> -	psc = (*delay_on * 152-1)/1000;
> -	err = pca9532_calcpwm(client, 0, psc, led_cdev->brightness);
> +	led->state = PCA9532_PWM1;
> +	err = pca9532_update_hw_blink(led, *delay_on, *delay_off);
>  	if (err)
>  		return err;
> -	if (led->state == PCA9532_PWM0)
> -		pca9532_setpwm(led->client, 0);
> +
>  	pca9532_setled(led);
>  
>  	return 0;
> -- 
> 2.44.0
> 

-- 
Lee Jones [李琼斯]