On Wednesday, April 11, 2012 03:20:24 PM J Igrap wrote: > On Wed, Sep 14, 2011 at 1:00 PM, Christian Lamparter > <chunkeey@xxxxxxxxxxxxxx> wrote: > > On Wednesday, September 14, 2011 03:09:14 PM J Igrap wrote: > >> On Wed, Sep 14, 2011 at 5:50 AM, Christian Lamparter > >>> On Tuesday, September 13, 2011 11:18:23 PM J Igrap wrote: > >>>> While using the past days the carl9170 firmware with a USB card under a > >>>> linux guest running different kernel and driver versions I kept running into > >>>> the issue of a usb disconnect when the card was put under load: > >>> linux guest? You are not using carl9170 in a VM, are you? > >>> > >> It is in a VM. I was working on a VM for ease of debugging the issue. > > So, I presume you have already tried running the driver natively > > and it fails in a similar fashion, right? [I just want to rule out > > a bug in the VM layers] > > > > Yes, it appears to fail in slow/older physicals too. what's "slower/older"? I know a few people reported problems with embedded USB HCDs but that's understandable. However, I occasionally test carl9170 on a 7 year old laptop and so far it runs ok. > >>>> usb 1-1: no command feedback received (-110). > >>>> carl9170 cmd: 08 01 00 00 f0 36 1c 00 00 24 00 00 .....6...$.. > >>>> usb 1-1: restart device (6) > >>>> > >>>> No matter what kernel driver/firmware I tried I will still get it. I decided > >>>> to look into it a bit more and I narrowed it down to be a firmware issue > >>>> with the following code snippet: > >>> Or it could be a problem with the USB PHY. However, the driver > >>> seems to be able to handle the situation and restarts the device > >>> accordingly. > >>> > >> I tried with several physical devices and they all seemed to have the > >> same behavior. The device does restart however you lose connectivity > >> and state of what you were doing. > > Any transmission protocol should be able to handle loss of connectivity. > > Furthermore all connection managers [wpa_supplicant, NetworkManager, wicd] > > will automatically reestablish the link if the device was put out by a > > catastrophic failure. > > > >>>> void handle_cmd(struct carl9170_rsp *resp) in src/cmd.c > >>>> > >>>> case CARL9170_CMD_WREG: > >>>> esp->hdr.len = 0; > >>>> for (i = 0; i < (cmd->hdr.len / 8); i++) > >>>> set(cmd->wreg.regs[i].addr, cmd->wreg.regs[i].val); > >>>> break; > >>>> > >>>> That code appears to handle event 1 which is a write into a register. In > >>>> some cases that write appeared to cause a failure and a reset into the card. > >>>> I added a simple delay loop before the switch statement and that seemed to > >>>> fix the issue and I don't lose the card anymore even under a lot of load. > >>>> Obviously that's not a real fix and something else more reliable needs to be > >>>> in place. > >>> Any idea what this "something" else might be? > >> > >> I'm not very familiar with how USB works, maybe someone with more > >> experience can shed some light here? It seems to me that the event > >> handling needs to be slowed down a little or add some kind of > >> verification. > > the usb protocol already incorporates some verification > > http://www.beyondlogic.org/usbnutshell/usb3.shtml > > > > furthermore, the driver counts each command frame, therefore it can > > detect whenever a frame was lost. > > It does detect it and restarwts the device, hoever when running under > VMware os r slower physicalit gets in the way since the device resets > very often. > > I tried build various firmware's as an experiment and I noticed that > the higher I set the Max Frame Length the more resistant it becomes. > The script I wrote basically sends > a beacon packet multiple times in monitor mode and has a counter of > how many packets went through before the card resets. Any ideas what > could be causing this? no. Unlike ath9k_htc fw, carl9170 does not have "space" to add any sophisticated tracer. So, you are stuck with the 1/2-bit LEDs as a window to the device. Regards, Christian -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
