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

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Date:	Tue, 07 Aug 2007 10:44:57 +0200
From:	David Engraf <david.engraf@...com.eu>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	Greg KH <gregkh@...e.de>, linux-pci@...ey.karlin.mff.cuni.cz,
	linux-kernel@...r.kernel.org, linux-usb-devel@...ts.sourceforge.net
Subject: Re: [linux-usb-devel] [PATCH] USB BIOS early handoff only when the
 we the driver is configured

You said your Intel board has also problems with the handoff.
Could you try the follwing patch, because the EHCI documentation
says that the OS must set the EHCI_USBLEGSUP_OS bit and then
wait until EHCI_USBLEGSUP_BIOS is cleared. The kernel never
uses the EHCI_USBLEGSUP_OS flag at the moment.
On my system there is no change, but maybe this patch works on
your system.

Thanks
David Engraf

linux-2.6.22.1

diff -puN drivers/usb/host/pci-quirks_orig.c drivers/usb/host/pci-quirks.c

--- drivers/usb/host/pci-quirks_orig.c    2007-07-10 20:56:30.000000000
+0200
+++ drivers/usb/host/pci-quirks.c    2007-08-07 10:38:33.000000000 +0200
@@ -268,6 +268,8 @@ static void __devinit quirk_usb_disable_
                  * handoff..
                  */
                 pci_write_config_byte(pdev, offset + 3, 1);
+
+                pci_write_config_byte(pdev, offset, cap |
EHCI_USBLEGSUP_OS);
             }
 
             /* if boot firmware now owns EHCI, spin till


Alan Stern schrieb:
> On Fri, 3 Aug 2007, David Engraf wrote:
>
>   
>> So we have hardware which has problems when we are not doing the
>> handoff, and hardware which has
>> problems when we are  doing the handoff...
>>     
>
> What hardware has problems when we do the handoff?  Your system and 
> mine experience a delay, but it doesn't break anything.
>
>   
>> What is the best way to solve the problem? Maybe a kernel parameter, a
>> config flag or an automatic
>> hardware dependent check of the system?
>> In fact it is hard to find a solution which works for both as long as
>> the hardware has this bugs.
>>     
>
> If we really need it, I say we should use a Kconfig flag.
>
> Alan Stern
>
>   

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