linux-kernel - Problem with libata-pata, ATAPI DVD reader and a "copy-protected" audio cd

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Date:	Sat, 03 Mar 2007 12:00:01 +0100
From:	GhePeU <ghepeu@...gilio.it>
To:	linux-kernel@...r.kernel.org
Subject: Problem with libata-pata, ATAPI DVD reader and a "copy-protected"
	audio cd

Hello,

when kernel 2.6.20 was released I switched to the new libata-pata
infrastructure for my EIDE hard disk and ATAPI dvd-reader. 

Until yesterday I didn't have any problem, then I tried to play an audio
CD and my media player hanged. Looking to the logs, I found that the DVD
reader (a Toshiba SD-M1612) was having problems reading the disk and
that the kernel dropped its speed from UDMA/33 to PIO3 before I could
eject the CD. Attached to this mail are the relevant lines of the system
log.

After a careful scrutiny of the box, I noticed that the disk was one of
those "Copy protected" non-standard CD. With the old ide driver I could
play and rip the CD without problems, so from a user point of view this
is a regression.

Besides, with the reduced speed the DVD reader was almost unusable, and
since the new libata layer doesn't support forcing the driver speed with
hdparm, I had to reboot the machine.

So my questions are:

1) it is possible to implement a command to force re-detection of the
better transfer mode available? I suppose that by unloading and
reloading the module, the transfer mode should become again the better
available, but when the driver is compiled in-kernel, this is not
possible.

2) is there a way to access copy protected audio CD again? the only
change here was ide -> libata, so there has to be some difference in the
error handling of the two layer that caused this pseudo-regression.

Thank you in advance

Giacomo

PS. I'm not subscribed to the list. I'm going to regularly check the
archives in the next days to see if there are responses, CC me if you
can. Thank you.

View attachment "DMA-drop.txt" of type "text/plain" (8195 bytes)