[Bug 53754] Re: ata_piix problem with Intel ICH7 chipset

[José M. López-Cepero]

A small update. Today I have struck a lucky chord: it's already almost
5h uptime and not a single hang (and, therefore, my wireless connection
is working happily). If I do a dmesg, the following suspicious lines
appear:

[17179641.092000] cdrom: sr0: mrw address space DMA selected
[17179641.116000] Assertion failed! qc->n_elem > 0,drivers/scsi/libata-core.c,ata_fill_sg,line=2531
[17179641.376000] cdrom: sr0: mrw address space DMA selected
[17179641.380000] Assertion failed! qc->n_elem > 0,drivers/scsi/libata-core.c,ata_fill_sg,line=2531

Whatever that means, I have not seen them before (and I don't remember
updating the kernel from yesterday to today). The system seems to work
perfectly fine, with no evident negative consequences of the failed
assertion, and with no hangs. The CD works seemingly OK, and copying
large files out of it doesn't clog the CPU, but the maximum transfer
speed seems to be around 2 MB/s. I'd rather endure that than the hangs.
If any of you know of any way to force the "mrw address space DMA", that
might be a good enough workaround for the moment...

I'll leave the computer running overnight to be sure, and then reboot
and see if it magically works again...

-- 
ata_piix problem with Intel ICH7 chipset
https://launchpad.net/bugs/53754