Re: [PATCH v6 2/4] leds: Add driver for Qualcomm LPG

Pavel Machek
2020-10-29T18:14:05Z

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Hi!

> The Light Pulse Generator (LPG) is a PWM-block found in a wide range of
> PMICs from Qualcomm. It can operate on fixed parameters or based on a
> lookup-table, altering the duty cycle over time - which provides the
> means for e.g. hardware assisted transitions of LED brightness.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> ---
>
> Changes since v5:
> - Make sure to not used the state of the last channel in a group to determine
> if the current sink should be active for all channels in the group.
> - Replacement of unsigned -1 with UINT_MAX
> - Work around potential overflow by using larger data types, instead of separate code paths
> - Use cpu_to_l16() rather than hand rolling them
> - Minor style cleanups
>
> drivers/leds/Kconfig | 9 +
> drivers/leds/Makefile | 1 +
> drivers/leds/leds-qcom-lpg.c | 1190 ++++++++++++++++++++++++++++++++++
> 3 files changed, 1200 insertions(+)
> create mode 100644 drivers/leds/leds-qcom-lpg.c

Let's put this into drivers/leds/rgb/. You may need to create it.

> +static int lpg_lut_store(struct lpg *lpg, struct led_pattern *pattern,
> + size_t len, unsigned int *lo_idx, unsigned int *hi_idx)
> +{
> + unsigned int idx;
> + __le16 val;

No need for __XX variants outside of headers meant for userspace.

> +#define LPG_ENABLE_GLITCH_REMOVAL BIT(5)
> +
> +static void lpg_enable_glitch(struct lpg_channel *chan)
> +{
> + struct lpg *lpg = chan->lpg;
> +
> + regmap_update_bits(lpg->map, chan->base + PWM_TYPE_CONFIG_REG,
> + LPG_ENABLE_GLITCH_REMOVAL, 0);
> +}
> +
> +static void lpg_disable_glitch(struct lpg_channel *chan)
> +{
> + struct lpg *lpg = chan->lpg;
> +
> + regmap_update_bits(lpg->map, chan->base + PWM_TYPE_CONFIG_REG,
> + LPG_ENABLE_GLITCH_REMOVAL,
> + LPG_ENABLE_GLITCH_REMOVAL);
> +}

Helper functions for single register write is kind of overkill...

> +static int lpg_blink_set(struct lpg_led *led,
> + unsigned long delay_on, unsigned long delay_off)
> +{
> + struct lpg_channel *chan;
> + unsigned int period_us;
> + unsigned int duty_us;
> + int i;
> +
> + if (!delay_on && !delay_off) {
> + delay_on = 500;
> + delay_off = 500;
> + }

Aren't you supposed to modify the values passed to you, so that
userspace knows what the default rate is?

> + ret = lpg_lut_store(lpg, pattern, len, &lo_idx, &hi_idx);
> + if (ret < 0)
> + goto out;

Just do direct return.

> +out:
> + return ret;
> +}

> +static const struct pwm_ops lpg_pwm_ops = {
> + .request = lpg_pwm_request,
> + .apply = lpg_pwm_apply,
> + .owner = THIS_MODULE,
> +};
> +
> +static int lpg_add_pwm(struct lpg *lpg)
> +{
> + int ret;
> +
> + lpg->pwm.base = -1;
> + lpg->pwm.dev = lpg->dev;
> + lpg->pwm.npwm = lpg->num_channels;
> + lpg->pwm.ops = &lpg_pwm_ops;
> +
> + ret = pwmchip_add(&lpg->pwm);
> + if (ret)
> + dev_err(lpg->dev, "failed to add PWM chip: ret %d\n", ret);
> +
> + return ret;
> +}

Do we need to do this? I'd rather have LED driver, than LED+PWM
driver...

Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek

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