linux-kernel - Re: [PATCH v15 3/8] mfd: simple-mfd-i2c: Enable support for the silergy,sy7636a

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Message-ID: <39b586c1-aba7-4d82-2c96-9f4ca9db4f11@roeck-us.net>
Date:   Wed, 24 Nov 2021 14:56:46 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andreas Kemnade <andreas@...nade.info>
Cc:     Alistair Francis <alistair23@...il.com>,
        Alistair Francis <alistair@...stair23.me>,
        Lee Jones <lee.jones@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>, lgirdwood@...il.com,
        Rob Herring <robh+dt@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        rui.zhang@...el.com, devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-hwmon@...r.kernel.org, amitk@...nel.org,
        linux-pm@...r.kernel.org, dl-linux-imx <linux-imx@....com>,
        Shawn Guo <shawnguo@...nel.org>
Subject: Re: [PATCH v15 3/8] mfd: simple-mfd-i2c: Enable support for the
 silergy,sy7636a

On 11/24/21 2:50 PM, Andreas Kemnade wrote:
> On Wed, 24 Nov 2021 12:09:44 -0800
> Guenter Roeck <linux@...ck-us.net> wrote:
> 
>> On 11/24/21 11:35 AM, Andreas Kemnade wrote:
>>> Hi,
>>>
>>> On Tue, 23 Nov 2021 07:39:05 -0800
>>> Guenter Roeck <linux@...ck-us.net> wrote:
>>>    
>>>> On 11/23/21 4:14 AM, Alistair Francis wrote:
>>>>> On Tue, Nov 16, 2021 at 9:10 AM Andreas Kemnade <andreas@...nade.info> wrote:
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> this all creates a lot of question marks...
>>>>>> One of my main question is whether sy7636a = sy7636 (at least the
>>>>>> driver in the kobo vendor kernels does not have the "A" at the end,
>>>>>> whic does not necessarily mean a difference).
>>>>>>
>>>>>> https://www.silergy.com/products/panel_pmic
>>>>>> lists only a SY7636ARMC, so chances are good that the letters were just
>>>>>> stripped away by the driver developers. Printing on chip package is
>>>>>> cryptic so it is not that helpful. It is just "BWNBDA"
>>>>>
>>>>> I don't have a definite answer for you. But I think it's sy7636a
>>>>>
>>>>> The page you linked to above lists SY7636ARMC as well as SY7627RMC,
>>>>> SY7570RMC. That makes me think that the RMC is a generic suffix and
>>>>> this actual IC is the SY7636A.
>>>>>       
>>>>
>>>> Almost all chips have an ordering suffix, indicating things like
>>>> temperature range or packaging. The datasheet says:
>>>>   
>>> yes, they have. The only question is where it starts. So did you find a
>>> public datasheet which you can chere
>>>    
>>
>> I registered an account on the Silergy web site, and I was subsequently
>> able to download the datasheet. The document has a "confidential"
>> watermark, so I can not share it. You should be able to register an
>> account and download it yourself, though.
>>
> ok, did so.
> 
>>>> Ordering Information
>>>> SY7636 □(□□)□
>>>>                | Temperature Code (C)
>>>>             | Package Code (RM)
>>>>           | Optional Spec Code (A)
>>>>
>>>> The datasheet otherwise refers to the chip as SY7636A.
>>>>   
>>> so there is no indication of something like this where the A really
>>> makes a difference:
>>>    
>>
>> I may be missing it, but I see nothing in the datasheet that would indicate
>> that or if the "A" has any relevance other than "Optional Spec Code",
>> and I do not see an explanation for that term either.
> 
> well things seems to match with things I got from analysing the kobo
> sources. So at least the thing in the Kobo Libra H2O seems to be that
> one described in the datasheet, so we can have one sy7636a driver for
> it.
> 
> BTW: If I search for a sy7636 on aliexpress I get some SO-8 lithium
> charger ICs.
> 

The datasheet says "PMIC for Electronic Paper Display".

Guenter