Re: [PATCH v4 2/4] leds: Add driver for Qualcomm LPG

Luca Weiss
2020-10-07T09:46:32Z

Hi Bjorn,

On Mon Sep 28, 2020 at 8:15 PM, Bjorn Andersson wrote:
> 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 v3:
> - Adopt multicolor model
> - Simplified hw_pattern implementation
>
> drivers/leds/Kconfig | 9 +
> drivers/leds/Makefile | 1 +
> drivers/leds/leds-qcom-lpg.c | 1213 ++++++++++++++++++++++++++++++++++
> 3 files changed, 1223 insertions(+)
> create mode 100644 drivers/leds/leds-qcom-lpg.c

<snip>

> +static int lpg_pwm_request(struct pwm_chip *chip, struct pwm_device
> *pwm)
> +{
> + struct lpg *lpg = container_of(chip, struct lpg, pwm);
> + struct lpg_channel *chan = &lpg->channels[pwm->hwpwm];
> +
> + return chan->in_use ? -EBUSY : 0;
> +}
> +
> +static int lpg_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> + const struct pwm_state *state)
> +{
> + struct lpg *lpg = container_of(chip, struct lpg, pwm);
> + struct lpg_channel *chan = &lpg->channels[pwm->hwpwm];
> +
> + lpg_calc_freq(chan, state->period / NSEC_PER_USEC);
> + lpg_calc_duty(chan, state->duty_cycle / NSEC_PER_USEC);

As written on IRC this has to be wrapped div_u64() to compile on arm32;
should also fix the buildbot failure.

> + chan->enabled = state->enabled;
> +
> + lpg_apply(chan);
> +
> + triled_set(lpg, chan->triled_mask, chan->enabled);
> +
> + return 0;
> +}

Other than that, this works great on msm8974-fairphone-fp2 (pm8941)
with reg 7 (red), 6 (green) & 5 (blue). Thanks for updating this
patchset!

Regards
Luca