Re: [PATCH v1 05/11] leds: aw200xx: calculate dts property display_rows in driver

[George Stark <gnstark@salutedevices.com>]

Hello Andy

On 10/9/23 16:20, Dmitry Rokosov wrote:
> On Fri, Oct 06, 2023 at 08:59:46PM +0300, Andy Shevchenko wrote:
>> On Fri, Oct 6, 2023 at 7:05 PM Dmitry Rokosov
>> <ddrokosov@salutedevices.com> wrote:
>>>
>>> From: George Stark <gnstark@salutedevices.com>
>>>
>>> Get rid of device tree property "awinic,display-rows" and calculate it
>>> in driver using led definition nodes. display-row actually means number
>>> of current switches and depends on how leds are connected to the device.
>>
>> So, how do we know that there will be no regressions on the systems
>> where this property is used in production?

There're two possible cases here if "awinic,display-rows" value is not 
equal to autocalculated value which is incorrect way of using the driver:

1) "awinic,display-rows" value was less then autocalculated value - it 
means that some leds never couldn't be turned on even if they are 
defined in dts. Now all defined leds can be controlled.

2)"awinic,display-rows" value was higher then autocalculated value -
it means that leds refresh cycle time was greater then it really needed 
due to controller spent time powering unconnected pins. It will affect 
leds' current but I consider it a kind of hack - the driver provides 
means to control current.

> 
> In the production boards, developers should set up the display-rows
> correctly; otherwise, the AW200XX LED controller will not function
> properly. In the new implementation, we calculate display-rows
> automatically, and I assume that the value will remain unchanged.
> 
>>> +               if (max_source < source)
>>> +                       max_source = source;
>>
>> max()  (will need minmax.h)?
> 
> Correct, I will fix it in the v2.
> 

-- 
Best regards
George