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Message-ID: <00715fd2-a866-9589-cfe1-d93fd6f9ed49@salutedevices.com>
Date:   Tue, 17 Oct 2023 02:30:26 +0300
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Subject: Re: [PATCH v1 05/11] leds: aw200xx: calculate dts property
 display_rows in driver
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To:     Dmitry Rokosov <ddrokosov@salutedevices.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
CC:     <lee@kernel.org>, <pavel@ucw.cz>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <conor+dt@kernel.org>,
        <kernel@sberdevices.ru>, <rockosov@gmail.com>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-leds@vger.kernel.org>
References: <20231006160437.15627-1-ddrokosov@salutedevices.com>
 <20231006160437.15627-6-ddrokosov@salutedevices.com>
 <CAHp75VeWwzg1spSvQ1tNmC7zVN1FLOjcpRGZsoL-49Di02pn0g@mail.gmail.com>
 <20231009132055.kg2gbbznr63plvm4@CAB-WSD-L081021>
From:   George Stark <gnstark@salutedevices.com>
In-Reply-To: <20231009132055.kg2gbbznr63plvm4@CAB-WSD-L081021>
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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