On Sat, 14 Oct 2006, Michael Thomson wrote:
> Hello folks
>
> I have been happily using an ATEN KVM switch (model CS-1742) for
> about a year with no discernable problems, dual-booting Fedora Core 5
> and Windows 2000 on one port, and my Mac on the other.
>
> I upgraded to a recent Fedora kernel (2.6.17-1.2187_FC5) via 'yum -
> upgrade' recently. This exposed an issue I'd been blithely unaware of
> on the previous kernel I'd used (2.6.16-1.2122_FC5). With the
> previous kernel, mouse and keyboard appear to work fine, but detailed
> logs shows lots that looks wrong to my eyes.
>
> With the 2.6.17 kernel, the issues seem to have passed some threshold
> and the keyboard is unusable via the KVM, though the mouse seems to
> work still.
>
> I have usbmon logs from both 2.6.16 and 2.6.17, and dmesg output with
> verbose logging that shows plenty of:
>
> usb 1-3.1: new device strings: Mfr=1, Product=2, SerialNumber=0
> usb 1-3.1: Product: CS-1742 V1.0.091
> usb 1-3.1: Manufacturer: ATEN Advance Tech Inc.
> usb 1-3.1: uevent
> usb 1-3.1: configuration #1 chosen from 1 choice
> usb 1-3.1: adding 1-3.1:1.0 (config #1, interface 0)
>
> ohci_hcd 0000:00:02.0: urb df585540 path 3.1 ep0out 5f120000 cc 5 -->
> status -110
> usb 1-3.1: failed to restore interface 0 altsetting 0 (error=-110)
>
> ohci_hcd 0000:00:02.0: urb df585ec0 path 3.1 ep1in 5e160000 cc 5 -->
> status -110
> usbhid 1-3.1:1.0: retrying intr urb
The log shows that about a half of the messages going between your
computer and the keyboard never get through. No wonder it's unusable!
> Upgrade the problem away:
> -----------------------
> I looked for any new firmware on the ATEN site, but can't see
> anything for the CS-1742 directly. I know it's related to other
> devices but there's nothing for the CS-1744 either and I didn't want
> to try the CS-1762 version 'just in case'.
>
> There were no more recent kernels directly from Fedora, and I
> couldn't see any relevant check-ins on the linus-usb-devel list, so
> decided not to try a vanilla kernel.org build. Should I have?
It probably wouldn't make any difference.
> Roll my own patches:
> --------------------
>
> I hoped that the fixes in hid-core.c for other ATEN devices might
> work, so I patched a custom 2.6.17-1.2187 kernel as follows:
>
> [EMAIL PROTECTED] usb]# cat ~mythtv/linux-2.6-usb-aten-cs-1742.patch
> --- linux-2.6.17.i686/drivers/usb/input/hid-core.c.orig 2006-06-18
> 02:49:35.000000000 +0100
> +++ linux-2.6.17.i686/drivers/usb/input/hid-core.c 2006-10-11
> 23:00:47.000000000 +0100
> + { USB_VENDOR_ID_ATEN, USB_DEVICE_ID_ATEN_CS1742,
> HID_QUIRK_NOGET },
> However I suspect this isn't as simple as I'd hoped. I got no joy
> from that attempt.
No, that quirk is not related to your problem.
It could be a matter of bad cabling, but it's much more likely that the
internal hub in the ATEN device is distorting or attenuating the signal
beyond your computer's ability to recognize. Or else maybe it's
interrupting the signal altogether. There's no way to tell exactly what's
happening without using a USB bus analyzer.
The older kernels just ignored these sorts of errors, whereas the new ones
take positive action and try resetting the device when no reply is
received. That's why the KVM worked better before.
If you want, it's possible to edit the source code for the USB HID driver
to make it revert to the earlier behavior of ignoring these errors.
Alan Stern
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