Hi Chr, On Wed, Sep 14, 2011 at 5:50 AM, Christian Lamparter <chunkeey@xxxxxxxxxxxxxx> wrote: > 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. >> 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. >> 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. Best, Jigrap > Regards, > Chr > -- 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
