quirks for C-Media Card Reader

Jost Menke cyberlab at gmx.de
Wed Mar 9 15:05:31 GMT 2005

Hi all,

I´m having some trouble with a 7 in 1 USB card reader with a C-Media CM-120
chip. The device is recognized as mass storage under Windows. In my first
attempt under 5.4-PRERELEASE #1, the device showed up as ugen0, so I
modified /usr/src/dev/usb/umass.c and /usr/src/dev/usb/usbdevs. I tried a
whole bunch of quirks and got the best results with the following


	vendor CMEDIA		0x0d8c	C-Media Inc.
	product CMEDIA CM120		0x5000	CM120 Card Reader 



After that, the device showed up as:

Mar  9 16:42:58 mymachine kernel: umass0: C-Media Inc. USB Card Reader, rev
1.10/1.00, addr 2
Mar  9 16:42:58 mymachine kernel: da0 at umass-sim0 bus 0 target 0 lun 0
Mar  9 16:42:58 mymachine kernel: da0: <  > Fixed Direct Access SCSI-0
Mar  9 16:42:58 mymachine kernel: da0: 1.000MB/s transfers
Mar  9 16:42:58 mymachine kernel: da0: 0MB (1213420628 0 byte sectors: 0H
0S/T 0C) 

But as you can see, da0 is said to have 0MB and when trying to mount it, the
system throws a kernel panic (integer divide fault).
Is there any other way than try and error to find the right quirks for this
device? Maybe someone can interpret the specifications supplied by the
vendor. They are available under


I saw that card readers with this chip are widely sold, so I think it would
be interesting to have it working.

Jost Menke

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