Kernel Bug Tracker – Bug 7547
(ata pktcddvd) libata reports error when ejecting CDs, lowers drive speed
Last modified: 2012-05-12 13:13:06 UTC
Most recent kernel where this bug did *NOT* occur:
Distribution: Debian unstable
Asus M2N-E (nVidia nForce 570 Ultra) motherboard
Plextor PX-712SA serial ATA DVD writer
As also reported in bug #7441 and bug #7460, with kernel 2.6.19-rc5 I had
major problems with audio CDs. Fortunately, with 2.6.19-rc6 these problems are
mostly gone; however one issue remains. When I eject a CD (it doesn't have to be
an audio CD, any CD will do) after it has been inserted and accessed by the
kernel, I get messages like this:
ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
ata5.00: tag 0 cmd 0xa0 Emask 0x4 stat 0x40 err 0x0 (timeout)
Then libata soft-resets the port and lowers the speed, which can go all the
way down to PIO0 if this happens many times. I'll be attaching my dmesg output
that illustrates this.
Steps to reproduce:
The final part of the (to be attached) dmesg output was produced simply by
repeatedly inserting a CD (an Ubuntu Dapper pressed CD) and executing the
mount /dev/dvdrw -t iso9660 -o ro,utf8 /cdrom
Created attachment 9558 [details]
dmesg output that exhibits this problem
Is this issue still present with kernel 2.6.20?
It's definitely still present with 2.6.20-rc3 that I'm using right now. But I
can try out the final version too one of those days and get back on you on that.
Indeed, it's still there even in the final version of 2.6.20.
OK, same with bug #7805, this problem is actually triggered by the packet writing stuff (CONFIG_CDROM_PKTCDVD), i.e. only after my init scripts have run:
pktsetup 0 /dev/scd0
which produces the following output on dmesg:
pktcdvd: writer pktcdvd0 mapped to sr0
I've since disabled that, and everything is fine. So as with the other bug, I guess you can either reassign it to a more suitable person / subsystem, or even close it altogether, dunno.
Pinging PKTCDVD maintainer.
Also, can you please report the failing log with 2.6.22-rc6?
Created attachment 11938 [details]
dmesg output of the problem, 2.6.22-rc7
Attaching a dmesg that demonstrates this with 2.6.22-rc7. The problem persists, but the error handling has changed. I.e. the kernel lowers the speed eventually to UDMA/25:PIO4, but then does not lower it any further (previous versions would go all the way to PIO0). I guess this is a good thing. :^)
Thanks for spending time on this Tejun.
Yeah, the speed down behavior has changed recently as going down to PIO buys nothing on SATA devices. It seems something is issuing START_STOP to the drive repeatedly and the drive just doesn't like it. I'll ask the PKTCDVD maintainer and cc Jens.
Any updates on this bug please, has it been resolved?