cvs commit: src/sys/cam/scsi scsi_da.c src/sys/dev/usb umass.c usbdevs

[Matthew Jacob]

>
> There are 3 kinds of devices:
>
> * SYNC CACHE works
> * SYNC CACHE reports an error, but continues working
> * SYNC CACHE just hangs, no error
> * SYNC CACHE reports and error correctly, but then all subsequent commands 
> time out
>
> We're talking about the 4th case and some versions with the 3rd case, if it 
> was possible to detect them without hanging (i.e. mode sense works and WCE 
> properly reported).  The problem is that we have a significant SYNC CACHE 
> quirk proliferation problem.
>
> A few years ago, we had a 6-byte command quirk proliferation problem, until I 
> modified USB and Firewire SIMs to report "not 6-byte capable". I then was 
> able to remove dozens of quirks and we seem to have solved that problem.  I'm 
> recommending we do the same thing with SYNC CACHE now.
>


Ah- I'm all for that as a reasonable solution as long as the default 
doesn't cause WCE off in a regular disk drive to be interpreted as "does 
not support".