port-cobalt/59023: IDE can't do DMA in NetBSD 10

[john%ziaspace.com@localhost]

>Number:         59023
>Category:       port-cobalt
>Synopsis:       IDE can't do DMA in NetBSD 10
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-cobalt-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jan 22 09:10:00 +0000 2025
>Originator:     john%ziaspace.com@localhost
>Release:        NetBSD 10.1_STABLE
>Organization:
	
>Environment:
	
	
System: NetBSD lily.zia.io 10.1_STABLE NetBSD 10.1_STABLE (LILY) #0: Wed Jan 22 05:16:42 UTC 2025 john%r7900.zia.io@localhost:/usr/obj-cobalt/sys/arch/cobalt/compile/LILY cobalt
Architecture: mipsel
Machine: cobalt
>Description:
	
With NetBSD <= 9, booting a GENERIC kernel works fine.
Booting a NetBSD 10 GENERIC kernel gives:

...
[   4.0398597] wd0 at atabus0 drive 0
[   4.0498926] wd0: <SATA SSD>
[   4.0498926] wd0: 476 GB, 992277 cyl, 16 head, 63 sec, 512 bytes/sect x 1000215216 sectors
[   5.0499003] swwdog0: software watchdog initialized
viaide0:0:0: lost interrupt
[  15.0598369]  type: ata tc_bcount: 512 tc_skip: 0
viaide0:0:0: bus-master DMA error: missing interrupt, status=0x20
[  15.0727954] wd0: excessive DMA errors - 4 in last 6 transfers
[  15.0727954] wd0d: DMA error reading fsbn 1000215215 (wd0 bn 1000215215; cn 992276 tn 15 sn 62), xfer 1f30, retry 0
[  16.0898364] wd0: soft error (corrected) xfer 1f30
[  16.0898364] WARNING: 3 errors while detecting hardware; check system log.
[  16.1031654] boot device: wd0
[  16.1031654] root on wd0a dumps on wd0b
viaide0:0:0: lost interrupt
[  26.1098372]  type: ata tc_bcount: 512 tc_skip: 0
viaide0:0:0: bus-master DMA error: missing interrupt, status=0x20
[  26.1227792] wd0d: DMA error reading fsbn 1000215215 (wd0 bn 1000215215; cn 992276 tn 15 sn 62), xfer 1f30, retry 0
[  26.6198364] wd0: soft error (corrected) xfer 1f30
viaide0:0:0: lost interrupt
[  36.6198364]  type: ata tc_bcount: 512 tc_skip: 0
viaide0:0:0: bus-master DMA error: missing interrupt, status=0x20
[  36.6327738] wd0d: DMA error reading fsbn 1000215215 (wd0 bn 1000215215; cn 992276 tn 15 sn 62), xfer 1f30, retry 0
[  37.1298364] wd0: soft error (corrected) xfer 1f30
[  37.1298364] root file system type: ffs
[  37.1435006] kern.module.path=/stand/cobalt/10.1/modules
viaide0:0:0: lost interrupt
...

and so on.
>How-To-Repeat:
	
Boot a GENERIC kernel with a drive that supports DMA.
>Fix:
	
Compiling a kernel with wd* at atabus? drive ? flags 0x0ff0 gives a working system.
Not sure how to fix the broken DMA.

I've had issues with IDE on Amiga and hpcarm machines, too, although I 
can't say with any certainty that this is related.

>Unformatted: