linux-kernel - Re: [PATCH v6 2/2] leds: rt5033: Add RT5033 Flash led device driver

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Date:	Tue, 01 Dec 2015 10:54:20 +0900
From:	Ingi Kim <ingi2.kim@...sung.com>
To:	Jacek Anaszewski <j.anaszewski@...sung.com>
Cc:	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	sameo@...ux.intel.com, lee.jones@...aro.org, rpurdie@...ys.net,
	inki.dae@...sung.com, sw0312.kim@...sung.com,
	beomho.seo@...sung.com, andi.shyti@...sung.com,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-leds@...r.kernel.org
Subject: Re: [PATCH v6 2/2] leds: rt5033: Add RT5033 Flash led device driver

Hi Jacek,

On 2015년 11월 30일 19:59, Jacek Anaszewski wrote:
> Hi Ingi,
> 
> On 11/30/2015 03:31 AM, Ingi Kim wrote:
>> Hi Jacek,
>>
>> On 2015년 11월 26일 18:43, Jacek Anaszewski wrote:
>>> Hi Ingi,
>>>
>>> On 11/26/2015 09:02 AM, Ingi Kim wrote:
>>> [...]
>>>>>> +torch_unlock:
>>>>>> +    mutex_unlock(&led->lock);
>>>>>> +    return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static int rt5033_led_flash_brightness_set(struct led_classdev_flash *fled_cdev,
>>>>>> +                       u32 brightness)
>>>>>> +{
>>>>>> +    struct rt5033_sub_led *sub_led = flcdev_to_sub_led(fled_cdev);
>>>>>> +    struct rt5033_led *led = sub_led_to_led(sub_led);
>>>>>> +
>>>>>> +    mutex_lock(&led->lock);
>>>>>> +    sub_led->flash_brightness = brightness;
>>>>>> +    mutex_unlock(&led->lock);
>>>>>
>>>>> Mutex protection is redundant in this case. You would need it if device
>>>>> state was also changed here.
>>>>
>>>> Okay, I'll remove it.
>>>>
>>>>>
>>>>> BTW why flash brightness can't be written to the device here?
>>>>>
>>>>
>>>> Flash brightness is only affected when FLED flashed (strobing).
>>>> So, I think it is better to be written in rt5033_led_flash_strobe_set function.
>>>
>>> strobe_set op should strobe the flash ASAP, and delegating brightness
>>> setting there extends a delay between calling strobe_set op
>>> and actual flash strobe. If you set the brightness here, then you
>>> wouldn't have to do that in the strobe_set op, of course unless the
>>> the brightness is altered through the API of the other LED, in two
>>> separate LEDs case.
>>>
>>
>> The brightness may be able to change its brightness in two separate LEDs case as you see.
>> So, I think it would be better to write brightness setting in strobe_op.
> 
> Could you motivate your statement, please? Why would it be better?
> 
>> In consideration of delay, of course, the brightness is set just when it would be changed.
> 
> I think that joint iout arrangement will be prevailing - this is the
> case for your board, isn't it? With the modification I am proposing
> the gain is clear.
> 

You're right, thanks.
Did you mean that flash attributes should be written
on their ops(flash brightness, flash timeout)?

let me update the driver on your suggestion.

>>>>>> +
>>>>>> +    return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int rt5033_led_flash_timeout_set(struct led_classdev_flash *fled_cdev,
>>>>>> +                    u32 timeout)
>>>>>> +{
>>>>>> +    struct rt5033_sub_led *sub_led = flcdev_to_sub_led(fled_cdev);
>>>>>> +    struct rt5033_led *led = sub_led_to_led(sub_led);
>>>>>> +
>>>>>> +    mutex_lock(&led->lock);
>>>>>> +    sub_led->flash_timeout = timeout;
>>>>>> +    mutex_unlock(&led->lock);
>>>>>
>>>>> Ditto.
>>>>>
>>>
>>> Timeout should be also written here.
>>>
>>
>> The timeout may be able to change its flash timeout in two separate LEDs case as you see.
>> So, I think it would be better to write timeout setting in strobe_op.
>> In consideration of delay, of course, the timeout is set just when it would be changed.
>>
>>> If you will add regmap_write in both ops, then mutex protection will
>>> have to be preserved, to assure consistency between registers state
>>> and sub_led->flash_brightness and sub_led->flash_timeout state.
>>>
>>
>> Thanks, but mutex protection is useless in this case.
>> so I try to remove it.
>>
>>>>
>>>>>> +#define RT5033_FLED_CTRL4_VTRREG_MAX    0x60
>>>>>
>>>>> Rename DEF to MASK.
>>>
>>> Hmm, here it should be: Rename MAX to MASK.
>>>
>>
>> Oh
>> Okay, Thanks :)
>>
> 
> 
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