From: Frans Pop <elendil@planet.nl>
To: Pavel Machek <pavel@suse.cz>
Subject: Re: HP accelerometer driver: testers wanted
Date: Fri, 23 Jan 2009 00:11:31 +0100
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References: <20090122213139.GD2159@elf.ucw.cz> <200901222301.57681.elendil@planet.nl> <20090122221708.GA3430@elf.ucw.cz>
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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 ‘main’:
hpfall.c:73: warning: passing argument 2 of ‘signal’ 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
19616
$ cat /sys/block/sda/device/unload_heads
0

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)?

Cheers,
FJP
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