usb wifi dongle stops working

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Hi,

I am debugging an issue for a USB device (usb wifi dongle from TP-LINK TL-WN321G which is using Ralink RT73 chipset). I am using it on an embedded board running Linux 2.6.30 on ARM architecture. When I configure the USB controller in USB 1.1 speed, my USB device (i.e. usb wifi dongle) works perfectly fine. But when the USB controller is configured for USB 2.0, the device stops working *after some time* when doing large data transfer at high speed.

The system becomes non-responsive. I could capture the USB packets (using analyzer) between controller and device and found that there was *continuous* PING - NAK token exchanges were happening. I could re-confirm this scenario by putting some debug prints in controller driver. From this observation, I assumed that it may happen that device is not able to release the buffers and because of that its sending NAK to each incoming PING request.

When I reduced the number of PINGs sent out by USB controller driver, the device was working fine. Currently I am skipping every alternate PING token from controller driver, but it is hitting network performance badly.

From my experiments, I found that USB host controller is working perfectly fine with mass storage devices. ALSO USB WiFi dongle is working fine with X86 platform (Desktop PC which has intel usb hcd). I found that USB wifi dongle has the same bulk in/out endpoints as of mass storage devices (i.e. no interrupt endpoints are present in dongle).

I am not sure in which direction I should debug further. Any inputs in same regard will be helpful.
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Thanks,
Viral Mehta,
Embedded Software Engineer,
Tel. No. 91 79 26563705, Ext. 423
www.einfochips.com <http://www.einfochips.com>
Prepare and Prevent rather than Repair and Repent
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