Re: [PATCH v10 2/2] leds: Add driver for Qualcomm LPG

Marijn Suijten
2021-10-27T21:26:45Z

Hi Bjorn,

On 2021-10-22 10:25:35, Bjorn Andersson wrote:
> On Sat 09 Oct 21:39 PDT 2021, Bjorn Andersson wrote:
>
> > The Light Pulse Generator (LPG) is a PWM-block found in a wide range of
> > PMICs from Qualcomm. These PMICs typically comes with 1-8 LPG instances,
> > with their output being routed to various other components, such as
> > current sinks or GPIOs.
> >
> > Each LPG instance can operate on fixed parameters or based on a shared
> > lookup-table, altering the duty cycle over time. This provides the means
> > for hardware assisted transitions of LED brightness.
> >
> > A typical use case for the fixed parameter mode is to drive a PWM
> > backlight control signal, the driver therefor allows each LPG instance
> > to be exposed to the kernel either through the LED framework or the PWM
> > framework.
> >
> > A typical use case for the LED configuration is to drive RGB LEDs in
> > smartphones etc, for which the driver support multiple channels to be
> > ganged up to a MULTICOLOR LED. In this configuration the pattern
> > generators will be synchronized, to allow for multi-color patterns.
> >
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> > ---
>
> Any feedback on this?

I asked in #linux-msm whether anything is wrong with the patterns,
since my Sony Discovery (sdm630 with a pm660l) blinks way quicker on a
pattern that's supposed to stay on for 1s and off for 1s:

echo "0 1000 255 1000" > /sys/class/leds/rgb\:status/hw_pattern

It however seems to be broken in the same way on an older version now
(this might be v9 or v8) which I don't remember to be the case. Can you
double-check if this is all working fine on your side? If so, I'll have
to find some time to debug it on my end.

Thanks!
- Marijn