linux-kernel - Re: [PATCH v2 0/3] ChromeOS Embedded Controller charge control driver

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: <db20a640-5323-4866-9968-c57391fbb6bc@amd.com>
Date: Wed, 5 Jun 2024 15:32:33 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Thomas Weißschuh <linux@...ssschuh.net>,
 Dustin Howett <dustin@...ett.net>
Cc: Benson Leung <bleung@...omium.org>, Guenter Roeck <groeck@...omium.org>,
 Sebastian Reichel <sre@...nel.org>, Lee Jones <lee@...nel.org>,
 chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org, Stephen Horvath <s.horvath@...look.com.au>,
 Rajas Paranjpe <paranjperajas@...il.com>
Subject: Re: [PATCH v2 0/3] ChromeOS Embedded Controller charge control driver

On 6/5/2024 04:33, Thomas Weißschuh wrote:
> On 2024-06-04 20:27:57+0000, Dustin Howett wrote:
>> On Mon, Jun 3, 2024 at 3:59 PM Thomas Weißschuh <linux@...ssschuh.net> wrote:
>>>
>>> Can you try disabling all of the Framework-specific charge control
>>> settings and test again?
>>> Probably the different, disparate logics in the Framework ECs are
>>> conflicting with each other.
>>
>> Fascinating! This board does indeed support charge limiting through
>> both interfaces. It looks like the most recently set one wins for a
>> time.
> 
> If it is the most recent one, shouldn't the driver have worked?
> What does "for a time" mean?
> I'm using only the upstream EC command and that seems to work fine.
> 
>> The UEFI setup utility only sets the framework-specific charge limit value.
>>
>> We should probably find some way to converge them, for all of the
>> supported Framework Laptop programs.
> 
> In the long term, Framework should align their implementation with
> upstream CrOS EC and either drop their custom command or make it a thin
> wrapper around the normal the upstream command.
> 
> (As you are familiar with EC programming maybe you want to tackle this?)
> 
> Until then I think we can detect at probe-time if the Framework APIs are
> available and use them to disable the Framework-specific mechanism.
> Then the CrOS EC commands should be usable.
> 
> The drawback is, that userspace using the Framework APIs will break
> the driver. That userspace would need to migrate to the standard UAPI.

How does userspace access the Framework APIs?  Surely it needs to go 
through the kernel?  Could you "filter" the userspace calls to block them?

For example this is something that currently happens in the dell-pc 
driver to block userspace from doing thermal calls and instead guide 
people to the proper API that the driver exports.

> 
> Also the settings set in the firmware would be ignored at that point.
> 
> I don't want to use the functionality of the Framework command because
> it's less featureful and I really hope it will go away at some point.