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Date: Wed, 24 Oct 2012 18:28:05 -0400 From: "Shawn J. Goff" <shawn.goff@...elecon.com> To: Bjørn Mork <bjorn@...k.no> CC: netdev <netdev@...r.kernel.org> Subject: Re: qmi-wwan bug On 10/24/2012 05:19 PM, Bjørn Mork wrote: > > "Shawn J. Goff" <shawn.goff@...elecon.com> wrote: > >> I've backported qmi-wwan to 2.6.39 (it's here: >> https://bitbucket.org/accelecon/linux-at91/changesets), and it mostly >> works, but I've come across a problem. The modem will sometimes stop >> responding to any qmi data (but the AT commands on the TTY ports keep >> working). This only happens when there is significant traffic flowing >> through the device (downloading a large file) while at the same time, >> AT >> commands are sent to one of the TTY ports (I first noticed with my own >> modem query program, but I can reproduce it using microcom to send >> "ATI\r" in a loop). > Using the tty ports should be completely independent of any qmi activity from the host perspective. I am tempted to claim this indicates a firmware bug. > >> I see this problem with different devices from >> different manufacturers. > Which still may use pretty much the same firmware, although a little less likely. > >> I've only made it happen on my kernel - I >> tried >> on 3.6.2, but it seems to not happen there. > Good. But I have a feeling that you switched more than just the kernel. Do you see the issue if you run your backport on the same hardware you tested 3.6.2 on? I just tested my 2.6.39 kernel on the same hardware that had 3.6.2; the problem is absent there. > > > I've also tried using a >> similar modem that uses a different driver (sierra-net) and that >> doesn't >> have the same problem. > Well, that is an entirely different firmware application and driver, even if the hardware is similar or even identical. Yes - I wanted to eliminate anything lower (such as usb-net? not sure if qmi-wwan uses that) from being a suspect contributor to the problem. > >> When it is in failure, if I try to ping an address, the system sends >> out >> several an ARP requests but gets no response. To get the device to >> respond again, I have to administratively set the wwan interface down, >> then up, use libqmi to get the connection going again, then dhcp to get >> >> an address. > Which sounds like the connection died. Does QMI work at this point, or is that dead too? Looks like qmi works. I can do --nas-get-signal-strength and it gives me good numbers. --wds-get-packet-service-status returns "Connection status: '2'" > >> I also have some USB traces of the failure and recovery process. I'm >> not >> familiar with CDC or QMI, so it's not yet clear to me exactly what's >> happening, but it looks like the modem just stops sending anything on >> its QMI endpoint for no reason. >> >> How might I dive further into the issue? So far, my next step is to >> look >> into CDC and QMI and try to decypher the USB traces. If anyone is >> interested, I can share a tcpdump or a USB trace. > I think a test of the backport on the same host hardware you run 3.6.2 on would be the best place to start. > > Bjørn Thanks for your help. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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