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

[George Stark]

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@xxxxxxxxxxxxxxxxx> wrote:
> > > From: George Stark <gnstark@xxxxxxxxxxxxxxxxx>
> > >
> > > 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