linux-kernel - Re: [PATCH v8 1/2] leds: flash: add driver to support flash LED module in QCOM PMICs

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Message-ID: <b06854ce-45e4-eeee-d5ec-51fb1d8d923f@quicinc.com>
Date:   Tue, 28 Mar 2023 16:13:57 +0800
From:   Fenglin Wu <quic_fenglinw@...cinc.com>
To:     Pavel Machek <pavel@....cz>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <lee@...nel.org>, <krzysztof.kozlowski@...aro.org>,
        <linux-leds@...r.kernel.org>, <quic_collinsd@...cinc.com>,
        <quic_subbaram@...cinc.com>, Luca Weiss <luca.weiss@...rphone.com>
Subject: Re: [PATCH v8 1/2] leds: flash: add driver to support flash LED
 module in QCOM PMICs



On 3/26/2023 1:36 AM, Pavel Machek wrote:
> On Fri 2023-03-03 17:50:22, Fenglin Wu wrote:
>> Add initial driver to support flash LED module found in Qualcomm
>> Technologies, Inc. PMICs. The flash module can have 3 or 4 channels
>> and each channel can be controlled indepedently and support full scale
>> current up to 1.5 A. It also supports connecting two channels together
>> to supply one LED component with full scale current up to 2 A. In that
>> case, the current will be split on each channel symmetrically and the
>> channels will be enabled and disabled at the same time.
>>
>> Signed-off-by: Fenglin Wu <quic_fenglinw@...cinc.com>
>> Tested-by: Luca Weiss <luca.weiss@...rphone.com> # sm7225-fairphone-fp4 + pm6150l
> 
>> +	flash->led_cdev.brightness_set_blocking = qcom_flash_led_brightness_set;
>> +
>> +	init_data.fwnode = node;
>> +	init_data.devicename = NULL;
>> +	init_data.default_label = NULL;
>> +	init_data.devname_mandatory = false;
>> +
>> +	rc = devm_led_classdev_flash_register_ext(dev, flash, &init_data);
>> +	if (rc < 0) {
>> +		dev_err(dev, "Register flash LED classdev failed, rc=%d\n", rc);
>> +		return rc;
>> +	}
> 
> I'd expect setting max_brightness somewhere around here.
> 
> What does cat /sys/class/leds/*/max_brightness say (and what directory
> name are you using)?

LED_FULL is used as the default max_brightness, the driver will do the 
calculation based on LED_FULL (as below) and set the corresponding 
current when brightness is updated :

u32 current_ma = brightness * led->max_torch_current_ma / LED_FULL;

This is how max_brightness shows on my device:

# cat /sys/class/leds/white:flash-0/max_brightness
255

> 
> BR,								Pavel