Re: sb600/sb700 ohci experimental patch

From: Andriy Gapon <avg_at_icyb.net.ua>
Date: Fri, 25 Sep 2009 11:11:40 +0300
on 25/09/2009 11:02 Svein Skogen (listmail account) said the following:
> Andriy Gapon wrote:
>> on 24/09/2009 17:51 Hans Petter Selasky said the following:
> 
> *SNIP!*
> 
>> Not sure how to interpret this.
>> Either a timing issue, i.e. the register gets over-written some time after we
>> program it.
>> Or perhaps a bug in SMM code, i.e. when we generate an SMI (e.g. while doing
>> ohci1 takeover) SMM code erroneously writes something to ohci0 ctrlhead.
>> Or something else... :)
> 
> Could it be related to "USB Legacy Devices" in bios, and thus be the
> same problem that was discussed recently (regarding HZ larger than 1000)?
> 
> An usb-legacy setup might explain both the register-changing _AND_ the
> timing issue...

It very well could, but...

We do perform proper OHCI takeover, so we don't expect firmware to mess with the
controllers after it is finished.

Also, I personally have everything "USB legacy" disabled in my BIOS ("USB Legacy
Support", "USB Keyboard support", "USB Mouse support"). Although, Gigabyte BIOSes
are known to be sometimes smarter than they appear and to "autodetect" things when
they are explicitly turned off in settings.

Last point. Explaining is half the job. Fixing / working around is the other half.

P.S. I am not sure what "timing issue" you referred to.

-- 
Andriy Gapon
Received on Fri Sep 25 2009 - 06:11:50 UTC

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