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Date: Thu, 18 Oct 2012 10:28:21 -0400 (EDT)
From: Alan Stern <stern@rowland.harvard.edu>
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To: Martin Vysny <vysny@baka.sk>
cc: Kernel development list <linux-kernel@vger.kernel.org>,
        USB list <linux-usb@vger.kernel.org>, <1062114@bugs.launchpad.net>
Subject: Re: usb issue on Intel chipset: abrupt mouse movements, usb keyboard
 loosing key events
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On Thu, 18 Oct 2012, Martin Vysny wrote:

> Good day,
>    thank you for your response, please see the answers below.
> 
> 
> On 10/17/2012 08:05 PM, Alan Stern wrote:
> > On Wed, 17 Oct 2012, Martin Vysny wrote:
> >
> >> Good day,
> >>     thank you for your mail. I was finally able to reproduce the issue. I
> >> am attaching a dmesg output of a correct boot (please note that there
> >> still are several unwanted IRQs), and a dmesg output of a reproduced error.
> >
> > Did you boot with the "irqpoll" option?  Judging by the log, it looks
> > like you did.
> >
> 
> Nope, I didn't boot with the irqpoll boot option enabled:
> $ cat /proc/cmdline
> BOOT_IMAGE=/boot/vmlinuz-3.5.0-17-generic 
> root=UUID=02dfb985-99c1-431d-882f-87475db02062 ro 
> crashkernel=384M-2G:64M,2G-:128M splash elevator=noop vt.handoff=7

Hmmm.  Maybe the kernel automatically polls disabled IRQs every 0.1 
second.

> >> [   67.512014] ehci_hcd 0000:00:1d.0: >Unwanted IRQ: c000 0
> >> [   67.512021] ehci_hcd 0000:00:1d.0: >Unwanted IRQ: e000 0
> >> [   67.512023] irq 17: nobody cared (try booting with the "irqpoll" option)
> >> [   67.512026] Pid: 0, comm: swapper/0 Tainted: G           O 3.5.0-17-generic #28
> >> [   67.512027] Call Trace:
> >> [   67.512034]  [<c10c6ae9>] __report_bad_irq+0x29/0xd0
> >> [   67.512037]  [<c10c6db5>] note_interrupt+0x175/0x1c0
> >> [   67.512041]  [<c1326d63>] ? intel_idle+0xc3/0x120
> >> [   67.512045]  [<c10c4bdf>] handle_irq_event_percpu+0x9f/0x1d0
> >> [   67.512047]  [<c10c4d4b>] handle_irq_event+0x3b/0x60
> >> [   67.512050]  [<c10c7710>] ? unmask_irq+0x30/0x30
> >> [   67.512052]  [<c10c775e>] handle_fasteoi_irq+0x4e/0xd0
> >> [   67.512053]  <IRQ>  [<c15d0692>] ? do_IRQ+0x42/0xc0
> >> [   67.512062]  [<c10689fe>] ? enqueue_hrtimer+0x1e/0x70
> >> [   67.512064]  [<c15d04f0>] ? common_interrupt+0x30/0x38
> >> [   67.512069]  [<c10400e0>] ? in_gate_area+0x10/0x50
> >> [   67.512071]  [<c1326d63>] ? intel_idle+0xc3/0x120
> >> [   67.512076]  [<c149b7b5>] ? cpuidle_enter+0x15/0x20
> >> [   67.512078]  [<c149bd18>] ? cpuidle_idle_call+0x88/0x220
> >> [   67.512081]  [<c101870a>] ? cpu_idle+0xaa/0xe0
> >> [   67.512086]  [<c159f715>] ? rest_init+0x5d/0x68
> >> [   67.512090]  [<c18b49be>] ? start_kernel+0x35d/0x363
> >> [   67.512092]  [<c18b44ed>] ? do_early_param+0x80/0x80
> >> [   67.512094]  [<c18b4303>] ? i386_start_kernel+0xa6/0xad
> >> [   67.512095] handlers:
> >> [   67.512098] [<c142fe00>] usb_hcd_irq
> >> [   67.512099] Disabling IRQ #17
> >> [   69.507175] ehci_hcd 0000:00:1d.0: >Unwanted IRQ: c000 0
> >> [   69.607118] ehci_hcd 0000:00:1d.0: >Unwanted IRQ: c000 0
> >
> > The debugging output show that the EHCI controller was not the source
> > of the unwanted IRQs.  And /proc/interrupts shows that ehci-hcd is the
> > only driver using IRQ #17, for the 0000:00:1d.0 device.

This should be stated more carefully.  The EHCI controller was not the 
source of the unwanted IRQs, unless it is somehow malfunctioning.

> > The most likely explanation is that there an interrupt-routing error
> > and some other device is causing these problems.  I don't know of any
> > easy way to find out what the other device is, however.
> >
> 
> Thanks for hinting at the probable source of the problem. I am new to 
> these things, but the /proc/interrupts lists IO-APIC-fasteoi. Perhaps 
> there may be some relation to some APIC issue?

There may be, but I don't know anything about that.  Somebody else will 
have to help.

Alan Stern

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