SCSI pass-through buffer alignment patch

[Hasso Tepper]

Matthew Dillon:
>     Hasso, please try this patch.  It is completely untested so I might
> have missed something.  It will also do a kprintf() when it hits the
> scsi/cam code that decides to realign the buffer:
>
> 	fetch http://apollo.backplane.com/DFlyMisc/cam01.patch

Success! I'm now able to blank DVD-RW several times without big problems, 
but for some reason it takes about 50 seconds instead 0.2 seconds it 
takes on DVD writer on my laptop (PATA, seems). But it works!

Writing works as well, but fixating takes about 400-500 seconds (it 
varies). This is same for both DVD writers I own though.

Using verbose output with cdrecord shows that it's a "flush cache" 
command:

Track 01: Total bytes read/written: 5955584/5955584 (2908 sectors).
Writing  time:   42.448s
Average write speed   0.1x.
Min drive buffer fill was 99%
Fixating...

Executing 'flush cache' command on Bus 2 Target 0, Lun 0 timeout 1000s
CDB:  35 00 00 00 00 00 00 00 00 00
cmd finished after 391.649s timeout 1000s

Executing 'test unit ready' command on Bus 2 Target 0, Lun 0 timeout 1000s
CDB:  00 00 00 00 00 00
cmd finished after 0.000s timeout 1000s
Fixating time:  391.650s


Maybe it's normal? I don't have DVD-R/DVD+R medium at the moment to test 
with though. There is a lot of "BOUNCING DATA" messages in dmesg 
obviously. I think that these should stay, but moved under some CAM_DEBUG 
ifdef.


-- 
Hasso Tepper