TRIM command not working - Kernel 3.2?

Question

linux

For some unknown reason, the trim does not work. I installed an SSD for myself, registered discard in fstab - the trim still did not work. OS - Debian Squeeze with kernel 3.2 from Backports, FS - ext4, did not disable logging, the system works in ACHI mode.
Command outputs and configs - below under the spoiler:
uname -a

$ uname -a
$ Linux erdees-netbook 3.2.0-0.bpo.2-686-pae #1 SMP Mon Apr 23 09:33:57 UTC 2012 i686 GNU/Linux

The trim was tested as follows:

# dd if=/dev/urandom of=tempfile count=10 bs=512k oflag=direct
# hdparm --fibmap tempfile
# hdparm --read-sector [ADDRESS] /dev/sda
# rm tempfile
# sync

After repeating step 3, no changes were observed.
fstab

$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# / was on /dev/sda1 during installation
UUID=eb07b6cb-e4ed-47a7-9518-19272a91a01a /               ext4   noatime,discard,errors=remount-ro 0    1
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
tmpfs /tmp tmpfs defaults 0 0
tmpfs /var/tmp tmpfs defaults 0 0
tmpfs /var/lock tmpfs defaults 0 0

dmesg | grep -c2 fs

[    0.156347] Brought up 2 CPUs
[    0.156425] Total of 2 processors activated (6666.08 BogoMIPS).
[    0.157046] devtmpfs: initialized
[    0.157046] PM: Registering ACPI NVS region at 7f69e000 (270336 bytes)
[    0.157046] print_constraints: dummy: 
--
[    0.312573] pci 0000:00:1d.7: PCI INT A disabled
[    0.312677] PCI: CLS 32 bytes, default 64
[    0.312798] Unpacking initramfs...
[    0.812392] Freeing initrd memory: 9320k freed
[    0.820263] audit: initializing netlink socket (disabled)
--
[    1.383550] atl1c 0000:01:00.0: PCI INT A -> GSI 19 (level, low) -> IRQ 19
[    1.383665] atl1c 0000:01:00.0: setting latency timer to 64
[    1.457277] usbcore: registered new interface driver usbfs
[    1.457436] usbcore: registered new interface driver hub
[    1.459375] SCSI subsystem initialized
--
[    4.046459]  sda: sda1
[    4.047279] sd 0:0:0:0: [sda] Attached SCSI disk
[    4.431266] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
[    4.780181] udev[278]: starting version 164
[    4.947507] input: Lid Switch as /devices/LNXSYSTM:00/device:00/PNP0C0D:00/input/input1
--
[    6.451865] psmouse serio1: synaptics: Touchpad model: 1, fw: 7.2, id: 0x1a0b1, caps: 0xd04733/0xa40000/0xa0000
[    6.531948] input: SynPS/2 Synaptics TouchPad as /devices/platform/i8042/serio1/input/input10
[    6.567201] EXT4-fs (sda1): re-mounted. Opts: (null)
[    6.615786] EXT4-fs (sda1): re-mounted. Opts: discard,errors=remount-ro
[    6.660193] loop: module loaded
[    7.150429] fuse init (API version 7.17)

PS - SSD - SSDNow V200 128 GB