[ath9k-devel] Disconnect problem (DMA failed to stop in 10 ms)

[Kunal Gangakhedkar <kunal.gangakhedkar@gmail.com>]

On Thursday 13 Aug 2009 11:10:42 am Pavel Roskin wrote:
> On Thu, 2009-08-13 at 10:51 +0530, Sujith wrote:
> > Pavel Roskin wrote:
> > > sync_cause is always 0x2000 when that message is printed, so there are
> > > no other causes.
> >
> > SYNC_LOCAL_TIMEOUT is generated when the PCIe core hangs, unable to
> > complete a DMA transfer. I am able to see this with 9280, 9281 and 9287.
> > So this seems to be a fundamental issue.
>
> Such issues are notoriously hard :-(
>
> If any ath9k version in the past didn't have that problem, I suggest
> bisection.
>
> Note that Michael noticed the performance degradation.  That's another
> target for bisection, whether it's related or not.

Any way we can help debug this issue?
It gets really annoying when the driver goes berserk in the middle of a big 
file transfer - even on LAN. :(

rmmod'ing and modprobe'ing the driver again seems to get it working; but, as 
the network load increases, the driver again starts faltering.

The problem starts especially under load on the network - say, while 
transferring ISOs from desktop to laptop, or updating ubuntu packages.

When the driver exhibits the problem, the ping times on the LAN also go 
berserk - ranging from ~1ms to ~700ms while sitting next to the wireless 
router (Linksys WRT54GL running OpenWRT Kamikaze 8.09) with packets lost.
The router is working fine because my other laptop (IBM Thinkpad R51 running 
ipw2200) never has any problems with the WLAN.

I'm using linux kernel 2.6.31-4-generic (x86_64) on kubuntu jaunty on this new 
HP laptop (dv6 series). The kernel is built by myself from ubuntu-karmic.git 
(git://kernel.ubuntu.com/ubuntu/ubuntu-karmic.git)

Config options related to ath9k in the kernel:

kunal at plutonium:/boot$ grep 'CONFIG_ATH9K' config-2.6.31-4-generic
CONFIG_ATH9K=m
CONFIG_ATH9K_DEBUG=y

The device info from 'lspci -vnn':
08:00.0 Network controller [0280]: Atheros Communications Inc. AR9285 Wireless 
Network Adapter (PCI-Express) [168c:002b] (rev 01)                               
        Subsystem: Hewlett-Packard Company Device [103c:3040]
        Flags: bus master, fast devsel, latency 0, IRQ 17
        Memory at d1200000 (64-bit, non-prefetchable) [size=64K]
        Capabilities: [40] Power Management version 3
        Capabilities: [50] Message Signalled Interrupts: Mask- 64bit- 
Queue=0/0Enable-
        Capabilities: [60] Express Legacy Endpoint, MSI 00
        Capabilities: [100] Advanced Error Reporting <?>
        Capabilities: [140] Virtual Channel <?>
        Capabilities: [160] Device Serial Number 12-14-24-ff-ff-17-15-00
        Capabilities: [170] Power Budgeting <?>
        Kernel driver in use: ath9k
        Kernel modules: ath9k

Please let me know if I can help in debugging.
Any patches that you might want me to try, I would be glad to give it a go.

Thanks,
-- 
Kunal