Re: ATA tape drive STT3401A needs DRQ HSM workaround too

[Albert Lee <albertcc@tw.ibm.com>]

Mark Lord wrote:
> Man.. somebody needs to teach hald the difference between optical drives
> and tape drives..   It seems to just sit in a tight loop issuing the same
> failed commands over and over and over to the tape unit after boot.
> 
> I had to kill it off to gain control of Fedora so I could actually *do*
> anything on the system.
> 
> Weird.
> 
> Any, Albert Lee has claimed the drive.
> 

Thanks for the drive.

After playing with the drive and checking the log, the DRQ+ERR problem only
happens when the tape drive is doing REQUEST SENSE. Also the DRQ=1 ERR=1
situation only happens when the tape drive wants us to transfer the CDB,
not the data.

It looks like the ERR=1 here is the residue of the previous command/error:
After an error and receiving the next PACKET command, the drive actually
wants the host to transfer the CDB of the next command (i.e. request sense)
by setting DRQ=1, but somehow it forgets to clear ERR to 0...

Maybe we can ignore the ERR bit if the command is REQUEST SENSE. Patch
to follow.
--
albert