linux-kernel - Re: [PATCH 2/4] pinctrl: amd: Drop pull up select configuration

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: <1149e5fe-2106-9b8d-d104-6668339d30cf@amd.com>
Date:   Mon, 3 Jul 2023 21:13:09 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     andy.shevchenko@...il.com,
        S-k Shyam-sundar <Shyam-sundar.S-k@....com>,
        Natikar Basavaraj <Basavaraj.Natikar@....com>
Cc:     linus.walleij@...aro.org, npliashechnikov@...il.com,
        nmschulte@...il.com, friedrich.vock@....de, dridri85@...il.com,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] pinctrl: amd: Drop pull up select configuration

On 7/3/23 16:32, andy.shevchenko@...il.com wrote:
> Fri, Jun 30, 2023 at 02:47:14PM -0500, Mario Limonciello kirjoitti:
>> pinctrl-amd currently tries to program bit 19 of all GPIOs to select
>> either a 4kΩ or 8hΩ pull up, but this isn't what bit 19 does.  Bit
>> 19 is marked as reserved, even in the latest platforms documentation.
>>
>> Drop this programming functionality.
> 
> Can it be that documentation is not (yet) updated?
> 

No; I double checked documentation across products from last few years 
as well as products to be coming out in the next few years and this bit 
is consistently marked "Reserved".

> Where, btw, did the original code come from? Perhaps it may shed some light
> on this.
> 

It's from the *very beginning* of the driver.

dbad75dd1f25 ("pinctrl: add AMD GPIO driver support.")

Original author isn't at AMD anymore, so I can't ask them.
I would guess that it was something that was discussed to be supported 
but never actually was.

Maybe Shyam and Basavaraj have some other thoughts on this bit.