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

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Message-id: <565BB510.2040903@samsung.com>
Date:	Mon, 30 Nov 2015 11:31:44 +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 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.
In consideration of delay, of course, the brightness is set just when it would be changed.

>>>> +
>>>> +    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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