linux-kernel - Re: [PATCH] EHCI pci-quirks.c: wait for BIOS handoff too long

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Message-ID: <20081105100050.GB1424@ucw.cz>
Date:	Wed, 5 Nov 2008 11:00:50 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	Steven Noonan <steven@...inklabs.net>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Greg KH <greg@...ah.com>, David Brownell <david-b@...bell.net>
Subject: Re: [PATCH] EHCI pci-quirks.c: wait for BIOS handoff too long

On Mon 2008-11-03 20:57:15, Steven Noonan wrote:
> Instead of waiting a painful 5000ms, quirk_usb_disable_ehci() now does a
> 1000ms loop to wait for the BIOS to acknowledge the handoff.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Alan Stern <stern@...land.harvard.edu>
> Cc: Greg KH <greg@...ah.com>
> Cc: David Brownell <david-b@...bell.net>
> Signed-off-by: Steven Noonan <steven@...inklabs.net>
> ---
>  drivers/usb/host/pci-quirks.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/usb/host/pci-quirks.c b/drivers/usb/host/pci-quirks.c
> index ae6e70e..1968ba1 100644
> --- a/drivers/usb/host/pci-quirks.c
> +++ b/drivers/usb/host/pci-quirks.c
> @@ -271,7 +271,7 @@ static void __devinit quirk_usb_disable_ehci(struct pci_dev *pdev)
>  			/* if boot firmware now owns EHCI, spin till
>  			 * it hands it over.
>  			 */
> -			msec = 5000;
> +			msec = 1000;
>  			while ((cap & EHCI_USBLEGSUP_BIOS) && (msec > 0)) {
>  				tried_handoff = 1;
>  				msleep(10);

If the bios is non-broken, it will acknowledge hndover and it takes
10msec total.

If the bios is broken, 5 seconds may be handy.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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