[Prism54-devel] [PATCH RFC] device reset in islpci_mgt_transaction()

[Denis Vlasenko]

Hi Jouni, Luis, Margit, Andreas,

prism54 was reported to sometimes die with iwconfig
no longer reporting any Wireless Extensions and
nothing working anymore. This can be fixed by fulfilling
TODO in islpci_mgt_transaction().

I did a patch (attached below) which does a reset
if hw times out.

Patch is not good enough for inclusion because:

1. Hang is detected and reset is triggered
only if islpci_mgt_transaction() is called from
somewhere (iwconfig <iface> will do). In 
pure acx100->prism54 flood test (no prism->acx
traffic at all), islpci_mgt_transaction() is never called
(or at least never times out).
Do we need a watchdog to periodically poll prism54 hw?

2. Busy-waiting is dirty.

Patch in action:

Jul 26 21:36:06 shadow kernel: Tx error occurred (error 0x20)!! (excessive Tx retries due to either distance too high or unable to Tx or Tx fr
Jul 26 21:36:18 shadow last message repeated 131 times
Jul 26 21:36:22 shadow kernel: ifp: timeout waiting for mgmt response 1000, triggering device
Jul 26 21:36:23 shadow default.hotplug[4078]: invoke /usr/app/hotplug-2004_01_05/script/firmware.agent ()
Jul 26 21:36:23 shadow kernel: ifp: timeout waiting for mgmt response
Jul 26 21:36:23 shadow kernel: ifp: scheduling a reset
Jul 26 21:36:23 shadow kernel: ifp: waiting for a reset to happen
Jul 26 21:36:23 shadow kernel: ifp: resetting device...
Jul 26 21:36:23 shadow kernel: ifp: uploading firmware...
Jul 26 21:36:23 shadow firmware.agent[4078]: /usr/app/hotplug-2004_01_05/firmware/isl3890 found, loading it into /sys//class/firmware/0000:00:
Jul 26 21:36:23 shadow kernel: ifp: firmware uploaded done, now triggering reset...
Jul 26 21:36:23 shadow default.hotplug[4093]: invoke /usr/app/hotplug-2004_01_05/script/firmware.agent ()
Jul 26 21:36:23 shadow kernel: ifp: reset done. Waited: 374 jiffies, 1721392 yields

Good news is that after reset card is happily doing its AP work.
Frankly, I didn't expect it to.
--
vda
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