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

Marijn Suijten
2021-10-27T21:27:48Z

On 2021-10-27 23:19:30, Marijn Suijten wrote:
> 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

Another thing I just ran into: on both patch revisions the colors are
flipped. multi_index reports "red green glue", but the values written
to multi_intensity correspond to "blue green red" instead. Is it the
same on your side?

- Marijn