Floppy keeps running forever after every access

In Ubuntu Precise, the floppy disk drive's motor keeps running forever as soon as the floppy is accessed (say, by doing a "mdir a:" or a "fdformat /dev/fd0", or a "dd if=/dev/fd0 ..." ), and the floppy drive's activity LED stays lit. Only when the disk is removed from the drive, the drive stops. I'd expect the drive to stop spinning a few seconds after the access is finished.

The accessing command returns normally and I can still access the drive normally by giving another command afterwards. The problem is purely the failure to deselect the drive and/or turn off the drive motor line.

This is a standard IRQ6/DMA2 floppy drive connected directly to the motherboard's built in FDC with a standard 34-wire ribbon floppy cable. The bug happens both with a normal 1.44MB drive and with a 1.2MB (5.25 inch) drive. The drives do not exhibit this problem in DOS or Windows running on the same physical hardware, and I do not remember having this problem in Oneiric either.

If you need more info on my system than the automatically generated attachments provide, please ask.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-23-generic 3.2.0-23.36
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
NonfreeKernelModules: nvidia
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu4
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: XFi [Creative X-Fi], device 0: ctxfi [Front/WaveIn]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: linards 1855 F.... pulseaudio
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
Card0.Amixer.info:
 Card hw:0 'XFi'/'Creative X-Fi 20K2 SB0880'
   Mixer name : '20K2'
   Components : ''
   Controls : 27
   Simple ctrls : 10
Date: Tue Apr 17 07:40:17 2012
HibernationDevice: RESUME=UUID=e00a04d9-b055-49bd-a504-bba24c74df32
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
IwConfig:
 lo no wireless extensions.

 teredo no wireless extensions.

 eth0 no wireless extensions.
MachineType: System manufacturer System Product Name
ProcFB:

ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-23-generic root=UUID=efe722f2-6b46-4b17-90a8-889d655827be ro quiet gfxpayload=text nomodeset quiet gfxpayload=text nomodeset
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-23-generic N/A
 linux-backports-modules-3.2.0-23-generic N/A
 linux-firmware 1.79
RfKill:

SourcePackage: linux
UpgradeStatus: Upgraded to precise on 2012-03-30 (17 days ago)
dmi.bios.date: 03/09/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 2104
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: P5B
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev 1.xx
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2104:bd03/09/2009:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP5B:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer