[Bug 88746] Re: ehci_hcd module causes I/O errors in USB 2.0 devices

Peter Hoeg peter at hoeg.com
Thu Dec 25 05:12:26 UTC 2008

Turns out the Intrepid standard kernel gives me the disconnects on my
main desktop too, although they don't make the machine lose connectivity
to the USB drives - things just work slowly for a brief moment and then
everything stabilises again. This machine has an nVidia MCP73 chipset.

The max_sectors fix seem however to do the trick, so here is a udev rule
that will make udev set the correct max_sectors on all USB drives
automatically and while YMMV it does in fact work for me.

It seems like the safe thing is to default max_sectors to 128 instead of
240 as it works with more chipsets and doesn't require kernel

Anyway, drop the following into
/etc/udev/rules.d/81-usb_max_sectors.rules and make sure that the
SUBSYSTEM line is in fact on one line and not broken into two.

# Set max_sectors to 128 for USB HDDs as the default 240 causes problems
SUBSYSTEM=="block", BUS=="usb", KERNEL=="sd*", RUN+="/bin/sh -c 'echo 128 > /sys/block/%k/device/max_sectors'"

I need this machine for work purposes so am a little hesitant to try out
the jaunty kernel especially since the workaround works and the
workaround can be implemented by policy as opposed to waiting for kernel

ehci_hcd module causes I/O errors in USB 2.0 devices
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