Re: [PATCH] reset USB controller

[Mikko Rantalainen <mikko.rantalainen@peda.net>]

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Vladimir 'phcoder' Serbinenko wrote:
> On Thu, Jul 16, 2009 at 5:56 PM, Robert Millan<rmh@aybabtu.com> wrote:
>> On Wed, Jul 15, 2009 at 10:51:55PM +0200, Vladimir 'phcoder' Serbinenko wrote:
>>> Hello, some BIOSes don't conform semaphore specification about handing
>>> over the control on UHCI and/or EHCI controller. Most OS cope with it
>>> by taking ownership regardless after some timeout. This however

Please, notice that the EHCI specification does not not specify the
required timeout. Especially, there's no timeout after which the forced
taking of ownership is safe.

See http://bugzilla.kernel.org/show_bug.cgi?id=12148 for further discussion.

Notice that once mainstream grub deals with USB keyboards without BIOS
support, the obvious fix is to disable the (buggy) USB legacy support in
the BIOS.

The other obvious fix would be to upgrade to non-buggy BIOS version but
unless your BIOS vendor fixes the issue, that's not really an option.

>> Is there some way we can make this simpler without compromising on boot
>> speed?  Adding more setup burden to the user should be the last ressort
>> IMO.
>>
> [...]
> Another usage is if OS doesn't deal with situation correctly.
> [...]
> If you consider this patch too hackish it can stay in my repo and
> people who really need can be said to use my repo or external module.
> If you consider this tweak possibility reasonable we can merge it

I don't know if the code quality is up to the requirements for getting
in the official trunk but I don't think that any method to deal with
broken BIOS or hardware cannot be too hackish. If the hardware (and this
includes the firmware) is broken and there's some hack that can make it
usable, just apply the hack. IMHO.

-- 
Mikko


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