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

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Message-id: <565C2C1A.3080100@samsung.com>
Date:	Mon, 30 Nov 2015 11:59:38 +0100
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Ingi Kim <ingi2.kim@...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 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.

>>>>> +
>>>>> +    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 :)
>


-- 
Best Regards,
Jacek Anaszewski
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