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List:       linux-usb-devel
Subject:    Re: [linux-usb-devel] Patch: Resume-fix for ehci-hub.c
From:       Stefan Rompf <srompf () isg ! de>
Date:       2004-10-14 8:22:41
Message-ID: 200410141022.44125.srompf () isg ! de
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Hi,

Am Freitag 08 Oktober 2004 00:25 schrieb David Brownell:

> Well there's a conceptual problem that keeps coming up lately...
> encouraged by the current APIs, to be sure!  The device doesn't

Yes, I'm following the discussion on LKML. However I have the impression that 
I need to read some additional specs before I reply there ;-)

> The problem is that when it's resumed after swsusp, it's really
> resuming from D3cold state ... and sometimes not even one
> of those, since BIOS may have mucked with the hardware.
> (Except for the S4BIOS suspend routes, I think...)

On my notebook (Fujitsu Amilo 7400), the USB controllers are not capable to 
restart the system according to /proc/acpi/wakeup_devices. Even if I cat 3 
to /proc/acpi/sleep, the USB bus is definitely unpowered while the ethernet 
controller that is able to wakeup stays enabled. Does that mean that EHCI 
actually goes to D3cold?

> The OHCI driver (in the current BK-USB tree) has code to
> specifically recognize some of the Funky BIOS States
> involved.  I haven't yet made time to see what those
> states are for EHCI; it's on my list...

Do you suggest that the driver should kill pending IO and force a 
reinitialisation of the root hub when power loss is detected? If so, I'll try 
to implement  it.

> handle, including ones like yours (BIOS doesn't
> seem to grok EHCI), or where the BIOS ignores
> both controllers, or where it also handles EHCI...

Well, actually the BIOS of my notebook does not care about most of the 
hardware on resume, without the generic PCI suspend/resume that went into 
2.6.7 or so nothing worked.

Stefan


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