Re: [PATCH v3 0/2] Add LED driver for flash module in QCOM PMICs

[Fenglin Wu]

On 2022/10/19 15:23, Luca Weiss wrote:
> Hi Fenglin,
>
> On Tue Oct 18, 2022 at 3:40 AM CEST, Fenglin Wu wrote:
> > Initial driver and binding document changes for supporting flash LED
> > module in Qualcomm Technologies, Inc. PMICs.
>
> Thanks for these patches, it's really nice to see drivers like this
> being sent upstream!
>
> I've just tried these patches on pm6150l which also is compatible with
> this driver (and used on sm7225-fairphone-fp4).
>
> The two different flash LEDs on the device I could adjust as expected
> using sysfs:
>
> $ echo 255 > /sys/class/leds/yellow:flash-0/brightness
> $ echo 255 > /sys/class/leds/white:flash-0/brightness
>
> Also lower brightness values resulted in lower brightness on the LED, so
> all is good here!
>
> But for flash usage, I couldn't figure out how to use it, doing the
> following resulted in no change on the LED.
>
> $ cat /sys/class/leds/white:flash-0/max_flash_brightness
> 1000000
> $ echo 1000000 > /sys/class/leds/white:flash-0/flash_brightness
>
> Here's my LED definition:
>
>    led-0 {
>      function = LED_FUNCTION_FLASH;
>      color = <LED_COLOR_ID_YELLOW>;
>      led-sources = <1>;
>      led-max-microamp = <180000>;
>      flash-max-microamp = <1000000>;
>      flash-max-timeout-us = <1280000>;
>    };
>
>  From values are from msm-4.19 kernel:
>
>    qcom,flash_0 {
>      qcom,current-ma = <1000>; // => flash-max-microamp
>      qcom,duration-ms = <1280>; // => flash-max-timeout-us
>      qcom,id = <0>; // => led-sources?
>    };
>
>    qcom,torch_0 {
>      qcom,current-ma = <180>; // => led-max-microamp
>      qcom,id = <0>; // => led-sources?
>    };
>
> Could you please let me know how flash is supposed to work or if I
> maybe have messed up some setting here?
>
> Regards
> Luca

Hi Luca,

Thanks for testing the driver at your end.
The "brightness" node is for enabling/disable/adjusting brightness when 
the LED is working in torch mode, the nodes for enabling/adjusting the 
LED behavior in flash mode are "flash_brightness" "flash_timeout" 
"flash_strobe".
You can strobe the flash by "echo 1 > flash_strobe" directly and the 
default brightness/timeout value will be used, or you can update the 
settings with "echo xxx > flash_brightness; echo xxx > flash_timeout" 
then strobe the LED with "echo 1 > flash_strobe". Please remember you 
always need to "echo 0 > flash_strobe" 1st if you want to enable it again.
Thanks

Fenglin
> > Changes in V3:
> >    1. Updated the driver to use regmap_field for register access.
> >    2. Adressed the review comments in binding document change.
> >
> > Changes in V2:
> >    1. Addressed review comments in binding change, thanks Krzysztof!
> >    2. Updated driver to address the compilation issue reported by
> >       kernel test robot.
> >
> >
> > Fenglin Wu (2):
> >    leds: flash: add driver to support flash LED module in QCOM PMICs
> >    dt-bindings: add bindings for QCOM flash LED
> >
> >   .../bindings/leds/qcom,spmi-flash-led.yaml    | 116 +++
> >   drivers/leds/flash/Kconfig                    |  15 +
> >   drivers/leds/flash/Makefile                   |   1 +
> >   drivers/leds/flash/leds-qcom-flash.c          | 700 ++++++++++++++++++
> >   4 files changed, 832 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/leds/qcom,spmi-flash-led.yaml
> >   create mode 100644 drivers/leds/flash/leds-qcom-flash.c
> >
> > --
> > 2.25.1