Re: [PATCH v1] leds: Clarify supported chips by LM355x driver

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On 01/30/2018 12:08 PM, Andy Shevchenko wrote:
> On Mon, 2018-01-29 at 21:46 +0100, Jacek Anaszewski wrote:
>> On 01/28/2018 03:30 PM, Andy Shevchenko wrote:
>>> On Fri, 2018-01-26 at 21:39 +0100, Jacek Anaszewski wrote:
>>>> On 01/26/2018 08:38 AM, Andy Shevchenko wrote:
>>>>> +	  Note, LM3555 is driven by AS3645A.
>>>>
>>>> Could you please provide more details on this relationship?
>>>> Looking at the datasheet it seems that both chips are standalone
>>>> and controlled via I2C and/or via GPIO in case of LM3555.
>>>
>>> The only difference I see looking in datasheets again that AS3645A
>>> supports dual-led mode, by using STROBE signal in case of parallel
>>> interface or thru additional bits in I2C mode.
>>>
>>> Can you be more specific what exactly makes you feel that they are
>>> not
>>> compatible?
>>
>> The expression "LM3555 is driven by AS3645A" brings on mind rather
>> some type of hardware dependency between chips than drivers
>> similarity.
>>
>> Now I understand that you meant that both devices can be driven by any
>> of leds-lm355x or leds-as3645a driver, am I right?
> 
> No. The chip in question is LM3555, and it's handled only in as3645a
> driver.
> 
>> I suspected that I got something entirely wrong here, especially
>> that both you and Pavel agreed.
>>
>> But, given that it turned out that leds-lm355x.c doesn't support
>> LM3555 and its documentation [3] indeed shows the affinity with
>> AS3645, I suppose that this patch is a result of a premature
>> conclusion drawn basing on the driver's description rather than its
>> capabilities.
>>
>> [3] http://www.ti.com/lit/ds/symlink/lm3555.pdf
>>
>> Effectively, the only sensible change seems to be:
>>
>> -	tristate "LED support for LM355x Chips, LM3554 and LM3556"
>> +	tristate "LED support for LM3554 and LM3556 chips"
>>  	depends on LEDS_CLASS && I2C
>>  	select REGMAP_I2C
>>  	help
>> -	  This option enables support for LEDs connected to LM355x.
>> -	  LM355x includes Torch, Flash and Indicator functions.
>> +	  This option enables support for LEDs connected to LM3554
>> +	  and LM3556. It includes Torch, Flash and Indicator
>> functions.
> 
> I like patch Pavel sent previously. It feels more comprehensive than
> this one.

Right. The patch subject and description will have to be tweaked a bit
then. I'll apply it once it is officially submitted.

-- 
Best regards,
Jacek Anaszewski



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