Date: Fri, 9 May 2003 14:28:28 -0700
From: Andrew Morton <akpm@digeo.com>
To: Paul Fulghum <paulkf@microgate.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: 2.5.69 Interrupt Latency
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Paul Fulghum <paulkf@microgate.com> wrote:
>
> In the process of eliminating kernel options to isolate
> the problem, eliminating USB completely appears to fix it.
> 
> One machine (server) was using usb-uhci and
> the other (laptop) was using usb-ohci.
> 
> So it looks like something with USB in 2.5.68-bk11

ah, that helps.

This code was added to wakeup_hc().  It is called from uhci_irq():

+	/* Global resume for 20ms */
+	outw(USBCMD_FGR | USBCMD_EGSM, io_addr + USBCMD);
+	wait_ms(20);

The changelog just says "Minor patch for uhci-hcd.c"

Can you delete the wait_ms() and see if that is our culprit?
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