On 03/01/2011 05:17 PM, Kushal Koolwal wrote:
I see the following group of exception messages (repeated 5 times)
when a IDE CD-ROM is present along with IDE hard drive on this Intel
Atom/Menlow system:
[ 4.278671] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6
[ 4.278769] ata1.00: BMDMA stat 0x64
[ 4.278856] ata1.00: failed command: READ DMA
[ 4.278950] ata1.00: cmd c8/00:20:70:ca:ab/00:00:00:00:00/e0 tag 0
dma 16384 in
[ 4.278953] res 51/84:00:8f:ca:ab/00:00:00:00:00/e0 Emask
0x10 (ATA bus error)
[ 4.279238] ata1.00: status: { DRDY ERR }
[ 4.279322] ata1.00: error: { ICRC ABRT }
[ 4.279429] ata1: soft resetting link
[ 4.656816] ata1.00: configured for UDMA/100
[ 4.688263] ata1.01: configured for UDMA/33
[ 4.689038] ata1: EH complete
[ 4.703657] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6
[ 4.703749] ata1.00: BMDMA stat 0x64
[ 4.703834] ata1.00: failed command: READ DMA
[ 4.703928] ata1.00: cmd c8/00:20:70:ca:ab/00:00:00:00:00/e0 tag 0
dma 16384 in
[ 4.703931] res 51/84:00:8f:ca:ab/00:00:00:00:00/e0 Emask
0x10 (ATA bus error)
[ 4.704163] ata1.00: status: { DRDY ERR }
[ 4.704249] ata1.00: error: { ICRC ABRT }
[ 4.704355] ata1: soft resetting link
[ 5.081245] ata1.00: configured for UDMA/100
[ 5.112262] ata1.01: configured for UDMA/33
[ 5.113026] ata1: EH complete
The system does boot fine ultimately and hdparm reports the correct
max. UDMA mode permissible on the system which is UDMA2 in this case.
The system uses 40 conductor cable. I do not see the above exception
messages when only IDE hard drive is present.
Giving the parameter libata.force=40c gets rid of these messages.
You shouldn't really use a 40-conductor cable in a system that has
devices that support faster than UDMA mode 2. Normally the kernel would
detect the 40-wire cable and block using faster speeds, but it seems
like the pata_sch driver doesn't support cable detection as the
cable_detect method is set to ata_cable_unknown (either because the
hardware doesn't support it or the author didn't bother to implement
it), so it can't detect this automatically.
It's possible that it works without the CD-ROM drive since there is less
electrical noise, etc. with only one device on the cable.
Attaching dmesg and lspci -vvvxxx output when both an IDE CD-ROM and
hard drive is present. I noticed that the D0TIM Bit30 (PPE) and D0TIM
Bit31 (USD) are both set by Linux kernel in the PCI config space of
the IDE controller.
Please let me know what other information I can provide in this regards.
Kushal Koolwal
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