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SubjectDMA problems on 440LX chipset
For quite a long time now in these pre-2.4.x kernels I've noticed
problems with DMA. Particularly with my cdrom, which is a Kenwood
52x TrueX ide drive. This is the info /proc gives me as detected by
linux.
/proc/ide/hdc/
model; KENWOOD CD-ROM UCR-412 V124I
driver; ide-cdrom version 4.58
settings;
name value min
max mode
---- ----- --- ---
----
breada_readahead 4 0
127 rw
current_speed 34 0
69 rw
dsc_overlap 0 0
1 rw
file_readahead 0 0
2097151 rw
ide_scsi 0 0
1 rw
init_speed 34 0
69 rw
io_32bit 0 0
3 rw
keepsettings 0 0
1 rw
max_kb_per_request 127 1 127
rw
nice1 1 0
1 rw
number 2 0
3 rw
pio_mode write-only 0
255 w
slow 0 0
1 rw
unmaskirq 0 0
1 rw
using_dma 0 0
1 rw

Now, I understand this cdrom is not a standard cdrom, so it may be using
non-standard DMA, but if that is so, then why when using hdparm, my
hdd's will also be finicky with DMA. I dont have any exact logs that
show what is really going on except of course the atapi driver puts my
cdrom in an infinite reset loop. It would be nice if I could force it
to stop doing that ... even if it means making the cdrom not accessible
because all it seems to do is increase load depending on what was
accessing it when the loop began. I usually have to turn the dma off on
the cdrom to get anything to access it now, although for some reason it
just stopped reading with 2.4.0-test7-pre7 ..it has power, but it wont
respond. Any help will be appreciated, I'm at a loss to explain what is
wrong. I was only aware of DMA problems on other non-standard
motherboards, this is a genuine intel 440LX .
Kernel options selected:
ALL the DMA options regarding "Use as default when available" and
"good bad firmware"
and Piix chipset support ( along with the correct for wrong value
option )
output of /proc/ide/piix
Intel PIIX4 Ultra 33 Chipset.
--------------- Primary Channel ---------------- Secondary Channel
-------------
enabled enabled
--------------- drive0 --------- drive1 -------- drive0 ----------
drive1 ------
DMA enabled: yes
yes no no
UDMA enabled: yes
yes no no
UDMA enabled: 2
2 X X
UDMA
DMA
PIO

The Cdrom is detected as "DMA" on boot but I turned it off with hdparm
because of the problems I mentioned before. The cdrom is supposed to be
UDMA2 like the other drives though (that's what the box said)
After looking in /proc/sys/dev/cdrom i set the "lock" file to 0
instead of 1, thinking maybe it was wrongfully locked and that's why it
wasn't responding ...but that didn't help so i set "debug' file to 1
and tried to eject the disc using the eject command
cdrom: entering CDROMEJECT
cdrom: entering cdrom_release
cdrom: Use count for "/dev/hdc" now zero
cdrom: Unlocking door!
....obviously the kernel knows something I don't, because the door is
still shut and the led didn't even light up.
so I tried mounting it and this is what I get
cdrom: entering cdrom_open
cdrom: entering open_for_data
cdrom: drive_status=4
cdrom: entering cdrom_count_tracks
ATAPI device hdc:
Error: Not ready -- (Sense key=0x02)
Unable to recover table of contents -- (asc=0x57, ascq=0x00)
The failed "Read Table of Contents" packet command was:
"43 02 00 00 00 00 00 00 04 00 00 00 "
cdrom: wrong media type, but CDO_CHECK_TYPE not set.
cdrom: all seems well, opening the device.
cdrom: opening the device gave me 0.
cdrom: device opened successfully.
cdrom: Use count for "/dev/hdc" now 1
VFS: Disk change detected on device ide1(22,0)
ATAPI device hdc:
Error: Not ready -- (Sense key=0x02)
Unable to recover table of contents -- (asc=0x57, ascq=0x00)
The failed "Read Table of Contents" packet command was:
"43 02 00 00 00 00 00 00 04 00 00 00 "
VFS: Disk change detected on device ide1(22,0)
ATAPI device hdc:
Error: Not ready -- (Sense key=0x02)
Unable to recover table of contents -- (asc=0x57, ascq=0x00)
The failed "Read Table of Contents" packet command was:
"43 02 00 00 00 00 00 00 04 00 00 00 "
hdc: irq timeout: status=0x80 { Busy }
hdc: ATAPI reset complete
ATAPI device hdc:
Error: Unit attention -- (Sense key=0x06)
Not ready to ready transition, medium may have changed -- (asc=0x28,
ascq=0x00)

and that repeats until mount timeouts and gives up. If there is any
other info needed to figure this out tell me and I'll get it. Thanks in
advance.

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