Re: HP accelerometer driver: testers wanted

From: Frans Pop
Date: Thu Jan 22 2009 - 18:11:43 EST

Minor issue in the patch: hpfall.c should not be executable:
-rwxr-xr-x 1 fjp fjp 1759 2009-01-22 23:31 hpfall.c

With patch applied:
$ ls -l /dev/freefall
crw-rw---- 1 root root 10, 59 2009-01-22 23:44 /dev/freefall

$ gcc -o hpfall -Os hpfall.c
hpfall.c: In function âmainâ:
hpfall.c:73: warning: passing argument 2 of âsignalâ from incompatible
pointer type

> Run hpfall, and see if LED lights and disk parks if you "drop" a
> computer. (*)

$ sudo ./hpfall &

The LED lights up yellow, but I have problems telling if the disk gets
parked or not. One time I got a green led and seemingly a fair amount of
activity immediately after getting the yellow led.

After looking at hpfall.c, I checked /sys/block/sda/device/unload_heads
after a drop:
$ cat /sys/block/sda/device/unload_heads
$ cat /sys/block/sda/device/unload_heads

The last was at most 2 seconds after the first, certainly not 20...

Wouldn't it be good to have locks/unlocks registered in the logs when
/sys/block/sda/device/unload_heads changes (assuming the actual write will
get delayed until the head is unparked)?

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