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Re: [PATCH] reset USB controller

From: Vladimir 'phcoder' Serbinenko
Subject: Re: [PATCH] reset USB controller
Date: Fri, 28 Aug 2009 22:41:27 +0200

On Thu, Jul 16, 2009 at 5:56 PM, Robert Millan<address@hidden> 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
>> increases booting time. Also some OSes don't cope with this quirk
>> correctly and are unable to access some devices. Here is a module to
>> forcibly remove BIOS ownership without timeout. It adds 2 commands:
>> ehcireste and uhcireset. I choose to name both functions analogously
>> even if actually only UHCI is really reset
> 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.
The only way I can think of is to have a quirk list. Most OS deal with
this situation properly and increased boot time by one up to few
seconds because of buggy BIOS is an acceptable compromise. This patch
is mainly as a optimisation trick if user knows about the problem.
Another usage is if OS doesn't deal with situation correctly. With
such OSes (I'm aware about some kinds of Darwin unless USB drivers are
corrected and not official from Apple) normal reaction would be to do
the long reset procedure but experience with USB drivers show that
fixing one thing may bring another bug. Once we have reliable USB
drivers we could just use their (long) ownership acquire function and
have an environment variable to do it hard and fast way.
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
> --
> Robert Millan
>  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
>  how) you may access your data; but nobody's threatening your freedom: we
>  still allow you to remove your data and not access it at all."
> _______________________________________________
> Grub-devel mailing list
> address@hidden

Vladimir 'phcoder' Serbinenko

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