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

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Date:   Wed, 19 Oct 2022 18:19:08 +0800
From:   Fenglin Wu <quic_fenglinw@...cinc.com>
To:     Luca Weiss <luca.weiss@...rphone.com>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <krzysztof.kozlowski@...aro.org>
CC:     <quic_collinsd@...cinc.com>, <quic_subbaram@...cinc.com>
Subject: Re: [PATCH v3 0/2] Add LED driver for flash module in QCOM PMICs



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
>