Re: [PATCH v2] leds: pca963x: enable low-power state

[Matt Ranostay <mranostay@gmail.com>]

> On Oct 19, 2016, at 23:08, Jacek Anaszewski <j.anaszewski@samsung.com> wrote:
> 
> Hi Matt,
> 
> Thanks for the update.
> Let me cc also authors of the driver.
> 
>> On 10/20/2016 02:03 AM, Matt Ranostay wrote:
>> Allow chip to enter low power state when no LEDs are being lit or in
>> blink mode.
>> 
>> Cc: Tony Lindgren <tony@atomide.com>
>> Cc: Jacek Anaszewski <j.anaszewski@samsung.com>
>> Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
>> ---
>> Changes from v1:
>> * remove runtime pm
>> * count leds that are off, if all then enter low-power state
>> 
>> drivers/leds/leds-pca963x.c | 24 +++++++++++++++++++++---
>> 1 file changed, 21 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/leds/leds-pca963x.c b/drivers/leds/leds-pca963x.c
>> index 407eba11e187..797dffc42c59 100644
>> --- a/drivers/leds/leds-pca963x.c
>> +++ b/drivers/leds/leds-pca963x.c
>> @@ -179,14 +179,32 @@ static void pca963x_blink(struct pca963x_led *pca963x)
>>    mutex_unlock(&pca963x->chip->mutex);
>> }
>> 
>> +static int pca963x_power_state(struct pca963x_led *pca963x)
>> +{
>> +    int i, leds_on = 0;
>> +
>> +    for (i = 0; i < pca963x->chip->chipdef->n_leds; i++) {
>> +        if (pca963x->chip->leds[i].led_cdev.brightness > 0)
>> +            leds_on++;
>> +    }
> 
> You could avoid executing this loop on every brightness setting,
> if you added a counter and incremented/decremented it when turning
> a LED on/off respectively. Then you could write PCA963X_MODE1 on
> counter transitions from 0 to 1 and from 1 to 0.

Thought of that but seems so low bandwidth it wouldn't matter. But have no issue adding a counter if required of course in v3
> 
>> +
>> +    return i2c_smbus_write_byte_data(pca963x->chip->client, PCA963X_MODE1,
>> +                     leds_on ? 0 : BIT(4));
>> +}
>> +
>> static int pca963x_led_set(struct led_classdev *led_cdev,
>>    enum led_brightness value)
>> {
>>    struct pca963x_led *pca963x;
>> +    int ret;
>> 
>>    pca963x = container_of(led_cdev, struct pca963x_led, led_cdev);
>> 
>> -    return pca963x_brightness(pca963x, value);
>> +    ret = pca963x_brightness(pca963x, value);
>> +    if (ret < 0)
>> +        return ret;
>> +
>> +    return pca963x_power_state(pca963x);
>> }
>> 
>> static int pca963x_blink_set(struct led_classdev *led_cdev,
>> @@ -391,8 +409,8 @@ static int pca963x_probe(struct i2c_client *client,
>>            goto exit;
>>    }
>> 
>> -    /* Disable LED all-call address and set normal mode */
>> -    i2c_smbus_write_byte_data(client, PCA963X_MODE1, 0x00);
>> +    /* Disable LED all-call address, and power down initially */
>> +    i2c_smbus_write_byte_data(client, PCA963X_MODE1, BIT(4));
>> 
>>    if (pdata) {
>>        /* Configure output: open-drain or totem pole (push-pull) */
>> 
> 
> 
> -- 
> Best regards,
> Jacek Anaszewski