atapicam & Promise [maybe PR/73675]

[Peter Wullinger]

Hello,

This is a strange, but non-critical one, and since I have no idea,
where to start, I should probably pass this on to folks who have
better knowledge of the code and hardware concerned:

The normal (disfunctional) configuration is:

atapci0
M	\- ad0
S	\- ad1
atapci1 (Via)
M	\- acd0 (dvdrom)
S	\- afd0 (zip)
atapci2 (Promise)
M	\- acd1 (burner)

When enabling atapicam and having my cd-burner attached to the third
ata channel, the kernel is unable to boot and hangs with an interrupt
storm. This happens on a GENERIC kernel as well as on my custom, 
stripped-down kernel.

Increasing the detection delay for interrupt storms to
	hw.intr_storm_threshold=15000
does not help. The occurence of the problem is also independent
from the fact, if the particular interrupt is shared between the
Promise controller and other hardware.  Controller (2.20.0.15) and
burner (1.04) firmware are newest available.

Switching to

atapci0
M	\- ad0
S	\- ad1
atapci1
M	\- acd1 (burner)
S	\- acd0 (dvdrom)
atapci2	
M	\- afd0 (zip)

however strangely remedies this problem. Cut-down dmesg output from a
non-working kernel is attached below.

This problem has surfaced in -CURRENT at around May, has persisted
since and is still present in 5_3_RELENG. I'm willing to provide 
additional debugging information (if somebody tells me how to get some),
test patches and the usual stuff, if anybody feels inclined to fix the
problem.

Cheers,
	Peter

[cc to søren and thomas assuming they are the most reasonable targets]

Motherboard: Asus A7M266

== dmesg ==
atapci0: <VIA 82C686B UDMA100 controller> port 0xd800-0xd80f,0x376,0x170-0x177,0x3f6,0x1f0-0x1f7 at device 4.1 on pci0
atapci1: <Promise PDC20269 UDMA133 controller> port 0x8800-0x880f,0x9000-0x9003,0x9400-0x9407,0x9800-0x9803,0xa000-0xa007 mem 0xe4800000-0xe4803fff irq 10 at device 11.0 on pci0
ad0: 117800MB <IC35L120AVV207-1/V24OA66A> [239340/16/63] at ata0-master UDMA100
ad1: 117800MB <IC35L120AVV207-1/V24OA66A> [239340/16/63] at ata0-slave UDMA100
acd0: DVDROM <MATSHITADVD-ROM SR-8585/1X32> at ata1-master UDMA33
afd0: REMOVABLE <IOMEGA ZIP 250 ATAPI/51.G> at ata1-slave BIOSPIO
acd1: CDRW <HL-DT-ST GCE-8520B/1.04> at ata2-master UDMA33
GEOM_VINUM: subdisk home.p1.s0 is up
GEOM_VINUM: subdisk home.p0.s0 is up
[...]
interrupt storm
== dmesg ==

-- 
Mut ist keine Vorbedingung für den Verlust des Lebens.
	-- Sir Peter Ustinov