Re: [linux-usb-devel] Re: Linux 2.6.x wrongly recognizes USB 2.0DVD writer

[Alan Stern]

On Thu, 14 Oct 2004, Ganesan R wrote:

> Thanks for the info. As I mentioned, the enclosure works flawlessly for 
> me under 2.4.27. It's getting detected incorrectly only in 2.6.x. 
> Another user reported a similar problem but was able to get dvd burning 
> working by removing the checks from the writing tool. So, it looks like 
> detection has been messed up only in 2.6.x.
> 
> Once again, 2.6.8 reports it as
> 
> ======
> scsi3 : SCSI emulation for USB Mass Storage devices
>   Vendor: Revoltec  Model: USB/IDE Bridge (  Rev: 0103
>   Type:   Direct-Access                      ANSI SCSI revision: 02
> Attached scsi removable disk sdb at scsi3, channel 0, id 0, lun 0
> ======
> 
> whereas 2.4.27 correctly reports
> 
> ========                                                               
> scsi2 : SCSI emulation for USB Mass Storage                            
>    Vendor: _NEC      Model: DVD_RW ND-2500A                            
>    Type:   CD-ROM    ANSI SCSI revision: 02                            
> Attached scsi CD-ROM sr1 at scsi2, channel 0, id 0, lun 0              
> sr1: scsi-1 drive                                                      
> USB Mass Storage support registered.                                   
> ========                                                               
> 
> I checked the kernel sources. Sure enough, 
> drivers/usb/storage/unusual_devs.h
> has a new entry in the 2.6 tree:
> 
> ========
> /* <torsten.scherer@xxxxxxxxxxxxxxxx>: I don't know the name of the bridge
>  * manufacturer, but I've got an external USB drive by the Revoltec company
>  * that needs this. otherwise the drive is recognized as /dev/sda, but any
>  * access to it blocks indefinitely.
>  */
> UNUSUAL_DEV(  0x0402, 0x5621, 0x0103, 0x0103,
>         "Revoltec",
>         "USB/IDE Bridge (ATA/ATAPI)",
>         US_SC_DEVICE, US_PR_DEVICE, NULL, US_FL_FIX_INQUIRY),
> ========
> 
> I have not yet tested after removing this entry, but this looks to be 
> the likely problem. The enclosure actually supports both 3.5 IDE hard 
> disks as well as 5.25 CD/DVD drives. I have no clue why this entry 
> should cause the drive to be wrongly detected. CCing linux-usb-devel for 
> help.

Certainly that entry is the problem.  It has been removed in the latest 
development kernels; it may already be gone in 2.6.9-rc4.

Alan Stern

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