linux-kernel - Re: [linux-usb-devel] [PATCH] USB BIOS early handoff only when the we the driver is configured

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Date:	Wed, 01 Aug 2007 09:21:12 +0200
From:	David Engraf <david.engraf@...com.eu>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	linux-kernel@...r.kernel.org, linux-pci@...ey.karlin.mff.cuni.cz,
	gregkh@...e.de, linux-usb-devel@...ts.sourceforge.net
Subject: Re: [linux-usb-devel] [PATCH] USB BIOS early handoff only when the
 we the driver is configured

At the moment I have a Jetway/VIA Mainboard which seems to have a
problem with the handoff.
Evenwhen I wait about 20 seconds the EHCI_USBLEGSUP_BIOS flag is not
cleared. I think this is a BIOS
bug and I will have to talk to Jetway/VIA.
On the other hand, I don't need the EHCI controller in my kernel, so I
think the kernel shouldn't take the
handover for the EHCI controller like other OS which do not have an usb
driver and so don't know that
there is a EHCI_USBLEGSUP_BIOS flag which should be cleared.

David Engraf


Alan Stern schrieb:
> On Tue, 31 Jul 2007, David Engraf wrote:
>
>   
>> When CONFIG_USB_UHCI_HCD, CONFIG_USB_OHCI_HCD or CONFIG_USB_EHCI_HCD is
>> not configured we don't need to call the quirk_usb_handoff_xxxx function
>> in driver/usb/host/pci_quiks.c.
>>
>> I think the kernel shouldn't take the control over the usb controller
>> when we don't have the driver for it,
>> so with this patch the kernel takes the control only when the driver is
>> configured.
>>     
>
> Have you found a system where this really improves behavior or is it 
> just theoretical?
>
> There _is_ a theoretical reason for running the handoff routines even 
> when the corresponding driver isn't configured.  Namely, at startup the 
> controller will be in some undetermined state as a result of usage by 
> the firmware.  Resetting it to a known idle state is a good idea.
>
> Bear in mind that on some systems, not performing the handoff has
> caused interrupt storms during startup.
>
> Alan Stern
>
>   
>

-- 
Mit freundlichen Grüßen

 

David Engraf

 

 
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