Re: [External] Re: [PATCH v3] i2c: i801: Safely share SMBus with BIOS/ACPI

[Hector Martin <marcan@marcan.st>]

On 18/12/2021 11.51, Alex Henrie wrote:
> On Fri, 17 Dec 2021 16:41:05 +0900
> Hector Martin <marcan@marcan.st> wrote:
> 
>> On 17/12/2021 09.31, Alex Henrie wrote:
>>> I am having a similar problem, but unfortunately this patch doesn't
>>> work for me (I get the error "BIOS uses SMBus unsafely"). Would it be
>>> acceptable to add a module parameter to allow access to the SMBus, even
>>> if the BIOS is using it? I realize that this is not a good idea in
>>> general, but I believe it is safe in my particular case, and I don't
>>> see any other way to solve my problem.
>>
>> How is this safe in your case? If the BIOS is using SMBus without
>> locking it, and may do so at any time, then there's no way to safely use
>> it from Linux.
> 
> The BIOS appears to access the SMBus during the first few minutes after
> boot, and then it stops using it. So "safe" may not be the right word,
> but in my case, it seems to work OK to use the SMBus as long as the
> uptime is greater than a few minutes.
> 
> -Alex
> 

Linux will probe the SMBus on startup, so that still seems like a rather
fragile situation. You'd have to blacklist the module and load it
separately a few minutes after boot, or something like that...

-- 
Hector Martin (marcan@marcan.st)
Public Key: https://mrcn.st/pub