[rt2x00-users] rt2800pci: hang on module unload (SoC) and possible fix

[Gertjan van Wingerde]

On 04/25/10 20:55, Helmut Schaa wrote:
> Am Sonntag 25 April 2010 schrieb Gertjan van Wingerde:
>> Sorry, I only just found this in my inbox.
> 
> No worries, that's alright ;)
> 
>> It looks like my rt2800pci based PCI devices suffer from the same issue.
>> However, your patch doesn't seem to help. On my system it simply speeds up
>> the hang.
> 
> Hmm, ok, that's bad :(
> 
> It did help on the SoC device. I can put the interface up and down as I like
> when using this patch. The hang does happen immediately when writing the
> WPDMA_RST_IDX register the first time (when the first tx queue is getting
> killed).

I can't find out when exactly it hangs right now. I'm testing on an EEE PC with
a RT3090 mini-PCIe adapter. I'm running an up-to-date Fedora 12 on it, using the
latest compat-wireless (with the latest rt2x00 patches applied).
Before the patch whenever I unloaded the module it took a few seconds before the
whole system hung, now it is immediately when unloading the module.
And it indeed is a complete machine hang.

> 
> When putting a printk in front of the register write and behind only the first
> one is printed out.
> 
> Can you locate where the PCI device hangs (btw does it hang the whole
> machine?)? Maybe it's a different hang on PCI, or maybe the patch just
> accidentelly helps on SoC devices :)
> 
>> I don't have the time right now to fully investigate this, but your patch
>> doesn't seem to fix the issue.
> 
> Ok, nevertheless, thanks for testing.
> 

Hopefully in the next few days I have the time to test this on a different machine
where I have an RT2860 PCI card in. Then it's easy to test from the console, and I can
see in a better way where it hangs.

---
Gertjan.