IRQ Routing issue? usb keyboard/mouse freezes when sata dvdrw connected on Dell Dimension C521

Binary package hint: linux-image-2.6.17-11-generic

After installation of ubuntu edgy 6.10 x64 in the past few weeks, I noticed that from time to time, the usb mouse or (less often) keyboard would "hang", in the sense that the computer would cease taking input from one or other. Otherwise, all would continue to work. The initial solution was to replug the offending USB device at which point it would go back to working again.

Coincidentally (or so I thought), I would also get pauses in xterms lasting a number of seconds. During the pause I could go to another application and work on. Keystrokes were queued by the xterm. I then noticed this message being repeated on average once/twice per minute in syslog/dmesg:

Mar 20 07:35:01 boing kernel: [664510.842378] ata2 failed to respond (30 secs)
Mar 20 07:35:01 boing kernel: [664510.852853] ata2: command 0xa0 timeout, stat 0xd0 host_stat 0x0
Mar 20 07:35:01 boing kernel: [664510.852861] ata2: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
Mar 20 07:35:01 boing kernel: [664510.839080] sr0: CDROM (ioctl) error, command: <6>Test Unit Ready 00 00 00 00 00 00
Mar 20 07:35:01 boing kernel: [664510.839088] sr: Current [descriptor]: sense key: Aborted Command
Mar 20 07:35:01 boing kernel: [664510.839091] Additional sense: Scsi parity error
Mar 20 07:35:07 boing kernel: [664515.912237] ata2 is slow to respond, please be patient

which seemed like it might be relevant. I unplugged the (evidently SATA) CDROM completely and since then all of the problems (usb freeze, dmesg errors, xterm pauses) have stopped.

According to its case, the cdrom is a DVD Writer Model TS-H653 (designed by Toshiba Samsung Storage Technology). Model TS-H563A / DEWH, F/W=D300, Ver. A, Dec 2006.

I am using the proprietary fglrx xorg module.

In case it reveals anything here is a syslog chunk which includes a usb replug (presumably due to it freezing):

Mar 20 13:40:16 boing kernel: [686423.824611] ata2 failed to respond (30 secs)
Mar 20 13:40:16 boing kernel: [686423.835119] ata2: command 0xa0 timeout, stat 0xd0 host_stat 0x0
Mar 20 13:40:16 boing kernel: [686423.835128] ata2: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
Mar 20 13:40:21 boing kernel: [686428.922396] ata2 is slow to respond, please be patient
Mar 20 13:40:45 boing kernel: [686452.519151] usb 1-4: USB disconnect, address 10
Mar 20 13:40:46 boing kernel: [686453.897072] ata2 failed to respond (30 secs)
Mar 20 13:40:46 boing kernel: [686453.907548] ata2: command 0xa0 timeout, stat 0xd0 host_stat 0x0
Mar 20 13:40:46 boing kernel: [686453.907557] ata2: translated ATA stat/err 0xd0/00 to SCSI SK/ASC/ASCQ 0xb/47/00
Mar 20 13:40:46 boing kernel: [686453.893679] sr0: CDROM (ioctl) error, command: <6>Test Unit Ready 00 00 00 00 00 00
Mar 20 13:40:46 boing kernel: [686453.893687] sr: Current [descriptor]: sense key: Aborted Command
Mar 20 13:40:46 boing kernel: [686453.893690] Additional sense: Scsi parity error
Mar 20 13:40:49 boing kernel: [686456.564936] ohci_hcd 0000:00:0b.0: IRQ INTR_SF lossage
Mar 20 13:40:51 boing kernel: [686458.966824] ata2 is slow to respond, please be patient
Mar 20 13:40:51 boing kernel: [686459.374773] usb 1-3: new low speed USB device using ohci_hcd and address 22
Mar 20 13:40:52 boing kernel: [686459.588904] usb 1-3: configuration #1 chosen from 1 choice
Mar 20 13:40:52 boing kernel: [686459.601941] input: DELL DELL USB Keyboard as /class/input/input20
Mar 20 13:40:52 boing kernel: [686459.601968] input: USB HID v1.10 Keyboard [DELL DELL USB Keyboard] on usb-0000:00:0b.0-3

lspci -v:
00:00.0 RAM memory: nVidia Corporation C51 Host Bridge (rev a2)
        Subsystem: nVidia Corporation C51 Host Bridge
        Flags: bus master, 66MHz, fast devsel, latency 0
        Capabilities: <access denied>

00:00.1 RAM memory: nVidia Corporation C51 Memory Controller 0 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 0
        Flags: 66MHz, fast devsel

00:00.2 RAM memory: nVidia Corporation C51 Memory Controller 1 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 1
        Flags: 66MHz, fast devsel

00:00.3 RAM memory: nVidia Corporation C51 Memory Controller 5 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 5
        Flags: 66MHz, fast devsel

00:00.4 RAM memory: nVidia Corporation C51 Memory Controller 4 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 4
        Flags: bus master, 66MHz, fast devsel, latency 0

00:00.5 RAM memory: nVidia Corporation C51 Host Bridge (rev a2)
        Subsystem: nVidia Corporation C51 Host Bridge
        Flags: bus master, 66MHz, fast devsel, latency 0
        Capabilities: <access denied>

00:00.6 RAM memory: nVidia Corporation C51 Memory Controller 3 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 3
        Flags: 66MHz, fast devsel

00:00.7 RAM memory: nVidia Corporation C51 Memory Controller 2 (rev a2)
        Subsystem: nVidia Corporation C51 Memory Controller 2
        Flags: 66MHz, fast devsel

00:02.0 PCI bridge: nVidia Corporation C51 PCI Express Bridge (rev a1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
        I/O behind bridge: 0000a000-0000afff
        Memory behind bridge: fda00000-fdafffff
        Prefetchable memory behind bridge: 00000000fd900000-00000000fd900000
        Capabilities: <access denied>

00:03.0 PCI bridge: nVidia Corporation C51 PCI Express Bridge (rev a1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=02, subordinate=02, sec-latency=0
        I/O behind bridge: 00008000-00008fff
        Memory behind bridge: fd800000-fd8fffff
        Prefetchable memory behind bridge: 00000000fde00000-00000000fde00000
        Capabilities: <access denied>

00:04.0 PCI bridge: nVidia Corporation C51 PCI Express Bridge (rev a1) (prog-if 00 [Normal decode])
        Flags: bus master, fast devsel, latency 0
        Bus: primary=00, secondary=03, subordinate=03, sec-latency=0
        I/O behind bridge: 0000b000-0000bfff
        Memory behind bridge: fdd00000-fddfffff
        Prefetchable memory behind bridge: 00000000d0000000-00000000dff00000
        Capabilities: <access denied>

00:09.0 RAM memory: nVidia Corporation MCP51 Host Bridge (rev a2)
        Subsystem: nVidia Corporation Unknown device cb84
        Flags: bus master, 66MHz, fast devsel, latency 0
        Capabilities: <access denied>

00:0a.0 ISA bridge: nVidia Corporation MCP51 LPC Bridge (rev a3)
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0

00:0a.1 SMBus: nVidia Corporation MCP51 SMBus (rev a3)
        Subsystem: Dell Unknown device 01f4
        Flags: 66MHz, fast devsel, IRQ 10
        I/O ports at 1c00 [size=64]
        I/O ports at 1c40 [size=64]
        Capabilities: <access denied>

00:0a.2 RAM memory: nVidia Corporation MCP51 Memory Controller 0 (rev a3)
        Subsystem: Dell Unknown device 01f4
        Flags: 66MHz, fast devsel

00:0b.0 USB Controller: nVidia Corporation MCP51 USB Controller (rev a3) (prog-if 10 [OHCI])
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 5
        Memory at fe02f000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: <access denied>

00:0b.1 USB Controller: nVidia Corporation MCP51 USB Controller (rev a3) (prog-if 20 [EHCI])
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 15
        Memory at fe02e000 (32-bit, non-prefetchable) [size=256]
        Capabilities: <access denied>

00:0e.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1) (prog-if 85 [Master SecO PriO])
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 11
        I/O ports at 09f0 [size=8]
        I/O ports at 0bf0 [size=4]
        I/O ports at 0970 [size=8]
        I/O ports at 0b70 [size=4]
        I/O ports at e000 [size=16]
        Memory at fe02d000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: <access denied>

00:0f.0 IDE interface: nVidia Corporation MCP51 Serial ATA Controller (rev a1) (prog-if 85 [Master SecO PriO])
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 10
        I/O ports at 09e0 [size=8]
        I/O ports at 0be0 [size=4]
        I/O ports at 0960 [size=8]
        I/O ports at 0b60 [size=4]
        I/O ports at cc00 [size=16]
        Memory at fe02c000 (32-bit, non-prefetchable) [size=4K]
        Capabilities: <access denied>

00:10.0 PCI bridge: nVidia Corporation MCP51 PCI Bridge (rev a2) (prog-if 01 [Subtractive decode])
        Flags: bus master, 66MHz, fast devsel, latency 0
        Bus: primary=00, secondary=04, subordinate=04, sec-latency=32
        I/O behind bridge: 00009000-00009fff
        Memory behind bridge: fdc00000-fdcfffff
        Prefetchable memory behind bridge: fdb00000-fdbfffff
        Capabilities: <access denied>

00:10.1 Audio device: nVidia Corporation MCP51 High Definition Audio (rev a2)
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 10
        Memory at fe024000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: <access denied>

00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
        Flags: fast devsel
        Capabilities: <access denied>

00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
        Flags: fast devsel

00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
        Flags: fast devsel

00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
        Flags: fast devsel
        Capabilities: <access denied>

03:00.0 VGA compatible controller: ATI Technologies Inc Unknown device 7183 (prog-if 00 [VGA])
        Subsystem: Dell Unknown device 0d02
        Flags: bus master, fast devsel, latency 0, IRQ 11
        Memory at d0000000 (64-bit, prefetchable) [size=256M]
        Memory at fddf0000 (64-bit, non-prefetchable) [size=64K]
        I/O ports at bc00 [size=256]
        [virtual] Expansion ROM at fdd00000 [disabled] [size=128K]
        Capabilities: <access denied>

03:00.1 Display controller: ATI Technologies Inc Unknown device 71a3
        Subsystem: Dell Unknown device 0d03
        Flags: fast devsel
        Memory at fdde0000 (64-bit, non-prefetchable) [disabled] [size=64K]
        Capabilities: <access denied>

04:07.0 Ethernet controller: Broadcom Corporation BCM4401-B0 100Base-TX (rev 02)
        Subsystem: Dell Unknown device 01f4
        Flags: bus master, fast devsel, latency 64, IRQ 5
        Memory at fdcfe000 (32-bit, non-prefetchable) [size=8K]
        Capabilities: <access denied>