Can't disable NCQ, /sys/block/sdc/device/queue_depth is readonly

["Roy Franz" <roy.franz@gmail.com>]

I can't disable NCQ due to the sysfs file being read-only:

amd64:/sys/block/sdc/device# ls -al queue_depth
-r--r--r-- 1 root root 0 2007-05-04 18:44 queue_depth
amd64:/sys/block/sdc/device#
amd64:/sys/block/sdc/device# echo 1 > queue_depth
bash: queue_depth: Permission denied
amd64:/sys/block/sdc/device#

I am running amd64 Etch, with this machine running a 2.6.20 kernel.  I checked
another AMD64 machine that is running the stock Debian 2.6.18-4 kernel
and the file is also readonly there.

This seems to be the officially supported way of enabling/disabling NCQ.

Has anybody else run into this or have a solution?

Thanks,
Roy
(Please copy me, I'm not subscribed.)