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

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Date:   Sun, 29 Sep 2019 15:01:49 +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 9/26/19 2:02 PM, Dan Murphy wrote:
> Jacek
> 
> On 9/25/19 5:00 PM, Jacek Anaszewski wrote:
>> 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?
> 
> I looked at this before sending it in.  This API adds the chan_num to
> write to.
> 
> The brightness_fn does not it takes it from the led structure.
> 
>>
>>> +{
>>> +    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)
> color_id and grouped_channels are not a 1:1 mapping

OK, they're channel numbers.

>> 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.

I've analyzed that design in greater detail and have started
to wonder why you can't pass two arrays to the new op:
channel numbers and corresponding calculated channel intensities?

-- 
Best regards,
Jacek Anaszewski