linux-kernel - Re: [PATCH] regulator: s5m8767: Convert to GPIO descriptors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7f22be3e-908d-4036-ab92-97c6b0427d26@kernel.org>
Date: Tue, 25 Mar 2025 10:30:16 +0100
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Peng Fan <peng.fan@....nxp.com>
Cc: Peng Fan <peng.fan@....com>, Andy Shevchenko
 <andriy.shevchenko@...el.com>, "lgirdwood@...il.com" <lgirdwood@...il.com>,
 "broonie@...nel.org" <broonie@...nel.org>,
 "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
 "brgl@...ev.pl" <brgl@...ev.pl>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "linux-samsung-soc@...r.kernel.org" <linux-samsung-soc@...r.kernel.org>,
 "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH] regulator: s5m8767: Convert to GPIO descriptors

On 24/03/2025 05:21, Peng Fan wrote:
> On Tue, Mar 18, 2025 at 02:48:05PM +0100, Krzysztof Kozlowski wrote:
>> On 18/03/2025 13:38, Peng Fan wrote:
>>>> Also the commit message doesn't tell anything about the existing DTS
>>>> files.
>>>> Do we have this device described in any in the kernel? Do we have any
>>>> googled examples? Why I'm asking because often the issue is the
>>>> incorrect setting of the polarity, which needs to be carefully checked,
>>>> esp. for the voltage regulators case.
>>>
>>>
>>> Under arch/arm/boot/dts/samsung/, a few dtsi files have the property 
>>> with results from output of
>>> `grep "s5m8767" ./arch/arm/boot/dts/samsung/ -rn | grep gpios`
>>>
>>> Exynos5250-spring.dts uses GPIO_ACTIVE_LOW.
>>> Others use GPIO_ACTIVE_HIGH.
>>>
>> These are old devices and not many people are actually providing tests,
>> so you need to preserve existing ABI. IOW, if previously GPIO flags were
>> ignored, meaning "1" is ACTIVE_HIGH, then you must preserve this behavior.
> 
> Per google,
> Manual Reset function is for Hardware reset in the Active mode.

Why are you mentioning the reset functions? Which properties are these?


> If MR1B and MR2B is kept low during the VLDO3 is active state, the
> system makes all internal presetting registers as default in the
> active mode (automatic power on sequence). If this hardware reset
> function is not required, connect MRB pin to high.
> 
> So the reset is ACTIVE LOW if my understanding is correct.
> 
> To keep DTS unchanged, we need update polarity in gpiolib to
> force GPIO_ACTIVE_LOW.

How are you going to achieve it if one DTS has LOW and other has HIGH?

> 
> please see whether this is ok for you.

I don't understand how this is related to the issue I raised.

Best regards,
Krzysztof