linux-kernel - Re: [PATCH 2/2] ARM: DTS: Add devicetree file for the Galaxy S2

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Date:   Tue, 31 Mar 2020 15:55:28 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>,
        Rob Herring <robh+dt@...nel.org>, mark.rutland@....com,
        Stenkin Evgeniy <stenkinevgeniy@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] ARM: DTS: Add devicetree file for the Galaxy S2

Hi Paul,

On 2020-03-31 15:09, Paul Cercueil wrote:
> Cc: Paweł Chmiel <pawel.mikolaj.chmiel@...il.com>
>
> Hi Marek,
>
> Le mar. 31 mars 2020 à 7:36, Marek Szyprowski 
> <m.szyprowski@...sung.com> a écrit :
>> Hi Paul,
>>
>> On 2020-03-18 15:25, Paul Cercueil wrote:
>>>>>   +    };
>>>>>   +
>>>>>   +    tsp_reg: regulator-1 {
>>>>>   +        compatible = "regulator-fixed";
>>>>>   +        regulator-name = "TSP_FIXED_VOLTAGES";
>>>>>   +        regulator-min-microvolt = <3300000>;
>>>>>   +        regulator-max-microvolt = <3300000>;
>>>>>   +        gpio = <&gpl0 3 GPIO_ACTIVE_HIGH>;
>>>>>   +        startup-delay-us = <70000>;
>>>>>   +        enable-active-high;
>>>>>   +        regulator-boot-on;
>>>>>   +        regulator-always-on;
>>>>
>>>>  always-on and boot-on should not be needed. You have a consumer 
>>>> for this
>>>>  regulator.
>>>
>>>  About this: the touchscreen driver does not use a regulator, so I
>>>  believe that's why these properties were here.
>>>
>>>  I sent patches upstream to address the issue:
>>>  https://protect2.fireeye.com/url?k=e8aedc29-b53072b3-e8af5766-0cc47a336fae-759579fd576d8382&u=https://lkml.org/lkml/2020/3/15/94 
>>>
>>>
>>>  I believe this means I cannot merge the i9100 devicetree until it is
>>>  acked.
>>
>> One more information - similar change has been already posted, but it
>> looks it got lost then: https://patchwork.kernel.org/patch/10550903/
>
> I was aware of this patch, but didn't know it was sent upstream.
>
> This other patch uses two regulators, vdd/avdd but doesn't give any 
> reason why.
>
I've checked the UniversalC210 schematic, which uses the same 
touchscreen chip. There are 2 supplies to the touchscreen chip: 2.8V VDD 
and 3.3V AVDD. Both are enabled by the same GPIO pin though. There is 
however no reset GPIO pin there.

> Paweł, is that really needed?
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland