linux-kernel - Re: [PATCH v9 13/15] leds: lp55xx: Update the lp55xx to use the multi color framework

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Date:   Thu, 26 Sep 2019 00:00:14 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Dan Murphy <dmurphy@...com>, pavel@....cz
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 13/15] leds: lp55xx: Update the lp55xx to use the multi
 color framework

Dan,

On 9/25/19 7:46 PM, Dan Murphy wrote:
> Update the lp5523 to allow the use of the multi color framework.
> 
> Signed-off-by: Dan Murphy <dmurphy@...com>
> ---
>  drivers/leds/Kconfig                      |   1 +
>  drivers/leds/leds-lp5523.c                |  13 ++
>  drivers/leds/leds-lp55xx-common.c         | 150 ++++++++++++++++++----
>  drivers/leds/leds-lp55xx-common.h         |  11 ++
>  include/linux/platform_data/leds-lp55xx.h |   6 +
>  5 files changed, 157 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 84f60e35c5ee..dc3d9f2194cd 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -377,6 +377,7 @@ config LEDS_LP50XX
>  config LEDS_LP55XX_COMMON
>  	tristate "Common Driver for TI/National LP5521/5523/55231/5562/8501"
>  	depends on LEDS_LP5521 || LEDS_LP5523 || LEDS_LP5562 || LEDS_LP8501
> +	depends on LEDS_CLASS_MULTI_COLOR && OF
>  	select FW_LOADER
>  	select FW_LOADER_USER_HELPER
>  	help
> diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
> index d0b931a136b9..8b2cdb98fed6 100644
> --- a/drivers/leds/leds-lp5523.c
> +++ b/drivers/leds/leds-lp5523.c
> @@ -791,6 +791,18 @@ static ssize_t store_master_fader_leds(struct device *dev,
>  	return ret;
>  }
>  
> +static int lp5523_led_intensity(struct lp55xx_led *led, int chan_num)

Why do we need this function? brightness op will not suffice?

> +{
> +	struct lp55xx_chip *chip = led->chip;
> +	int ret;
> +
> +	mutex_lock(&chip->lock);
> +	ret = lp55xx_write(chip, LP5523_REG_LED_PWM_BASE + chan_num,
> +		     led->brightness);
> +	mutex_unlock(&chip->lock);
> +	return ret;
> +}
> +
>  static int lp5523_led_brightness(struct lp55xx_led *led)
>  {
>  	struct lp55xx_chip *chip = led->chip;
> @@ -857,6 +869,7 @@ static struct lp55xx_device_config lp5523_cfg = {
>  	.max_channel  = LP5523_MAX_LEDS,
>  	.post_init_device   = lp5523_post_init_device,
>  	.brightness_fn      = lp5523_led_brightness,
> +	.color_intensity_fn = lp5523_led_intensity,
>  	.set_led_current    = lp5523_set_led_current,
>  	.firmware_cb        = lp5523_firmware_loaded,
>  	.run_engine         = lp5523_run_engine,
> diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
> index 44ced02b49f9..0e4b3a9d3047 100644
> --- a/drivers/leds/leds-lp55xx-common.c
> +++ b/drivers/leds/leds-lp55xx-common.c
> @@ -136,9 +136,26 @@ static int lp55xx_set_brightness(struct led_classdev *cdev,
>  {
>  	struct lp55xx_led *led = cdev_to_lp55xx_led(cdev);
>  	struct lp55xx_device_config *cfg = led->chip->cfg;
> +	int brightness_val[LP55XX_MAX_GROUPED_CHAN];
> +	int ret;
> +	int i;
> +
> +	if (led->mc_cdev.num_leds > 1) {
> +		led_mc_calc_brightness(&led->mc_cdev,
> +				       brightness, brightness_val);
> +		for (i = 0; i < led->mc_cdev.num_leds; i++) {
> +			led->brightness = brightness_val[i];
> +			ret = cfg->color_intensity_fn(led,
> +						      led->grouped_channels[i]);

Now we will have three separate calls for each color component
(and possibly sleeping on mutex on contention).

Probably LED mc class use case will need a bit different design.

Also, instead of grouped_channels we could possibly have

led_mc_get_color_id(&led->mc_dev, i)

which would map entry position index to color_id.

I will stop reviewing here and will continue after taking
deeper look at this lp55xx design.

-- 
Best regards,
Jacek Anaszewski