linux-kernel - Re: [PATCH v3] hwmon: (cros_ec) Add set and get target fan RPM function

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: <aa034893-405e-4f71-8cb6-0ccb112c36da@roeck-us.net>
Date: Tue, 25 Mar 2025 05:55:07 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Sung-Chi Li <lschyi@...omium.org>
Cc: Thomas Weißschuh <thomas@...ssschuh.net>,
 Jean Delvare <jdelvare@...e.com>, Benson Leung <bleung@...omium.org>,
 Guenter Roeck <groeck@...omium.org>, chrome-platform@...ts.linux.dev,
 linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] hwmon: (cros_ec) Add set and get target fan RPM
 function

On 3/25/25 00:16, Sung-Chi Li wrote:

> 
> Currently, when sending the fan control setting to EC, EC will switch to manual
> fan control automatically. When system suspends or shuts down, fans are going
> back to automatic control (based on current EC implementation).
> 
> Do you mean the driver should not change the fan control method if there is no
> pwmY_enable implemented, or it is the user that should first explicitly set the
> fan to manualy mode, then the user can specify the desired fan speed?

The user should first set the fan control method to manual mode.

Unless I am missing something, setting manual mode means that pwmY_enable does have
to be implemented.

Note that the suspend/resume behavior is unexpected. The user would assume that the fan
control method is still in the same mode after resume. If resume reverts to automatic mode,
there should be a suspend/resume handler which restores the mode on resume.

Thanks,
Guenter