Re: DMA appears broken in 2.6.11 for Mac 7200

Ben Said:

On Mon, 2005-03-14 at 03:51 +0000, linuxppcdev@qbjnet.com wrote:

quoted

Just updated a couple of old Mac 7200 (601) boxen and ran into trouble with
the ide driver and a promise PDC20267 card. 

The very same drives and card work fine on a 9500 but hang on a 7200. If
I set the kernel arg ide=nodma I get in the dmesg:
ide_setup: ide=nodma : Prevented DMA
and the 7200 boots and runs fine.

Another suspect, the mace ethernet driver (which also appears to use DMA)
doesn't work on the 7200 with 2.6.11 but does with 2.4.28 and it works 
with 2.6.11 on the 9500.

Interesting. Not sure what's up, though. Those old machines were known
to have bugs relative to cache coherency... also check wetehr we are
setting the cache line size properly in PCI devices. You can also try to
disable use of PCI memory write & invalidate command in all devices.

 
Did some more testing on this. Built a 2.4.30-pre1 kernel from bk source.

DMA works fine booting 2.4.30

I compared the dmesg and lspci and I see no differences in the cache line
size.

Is it possible that the ppc 601 kernel fixes aren't getting done properly
in 2.6??

Bob