On Wed, Jul 6, 2016 at 3:42 PM, Johan Hovold <johan@xxxxxxxxxx> wrote: > [ +CC: linux-usb, for real this time ;) ] > > On Wed, Jul 06, 2016 at 02:40:25PM +0530, Malith Yapa wrote: >> On Wed, Jul 6, 2016 at 2:13 PM, Johan Hovold <johan@xxxxxxxxxx> wrote: >> > [ Please avoid top-posing. ] >> > >> > On Wed, Jul 06, 2016 at 03:49:15AM +0000, Malith Yapa wrote: >> >> I'm polling a couple of input bits as well as 16 bit memory registers from >> >> a PLC (xinje) using libmodbus. >> > >> > Ah, so just normal tty use. >> > >> >> Feb 23 09:59:34 localhost kernel: [16960.073287] usb 5-1: USB disconnect, >> >> device number 11 >> >> Feb 23 09:59:34 localhost kernel: [16960.080069] usb 5-1: >> >> pl2303_read_int_callback - usb_submit_urb failed with result -19 >> > >> > You're getting these -ENODEV (-19) error because the pl2303 device has >> > already given up (crashed) and been disconnected. >> > >> >> Feb 23 09:59:35 localhost kernel: [16960.426637] usb 5-1: new full-speed >> >> USB device number 12 using sw-ohci >> >> Feb 23 09:59:35 localhost kernel: [16960.649900] usb 5-1: pl2303 converter >> >> now attached to ttyUSB10 >> > >> >> Any pointers for a workaround at the driver level? I could see that ENODEV >> >> results with the wrong device status. could that status be device 'busy'? >> >> will it help if i reduce my polling rate? >> > >> > I don't think there's anything to be done at the driver level I'm >> > afraid. If I understand you correctly, you're just using the normal tty >> > interface (e.g. through libmodbus) to access some external entity (and >> > its registers). >> > >> > Something is causing the pl2303 device to be reset. Perhaps an >> > electrical issue. >> > >> >> On Tue, Jul 5, 2016 at 6:09 PM Johan Hovold <johan@xxxxxxxxxx> wrote: >> >> >> >> > On Mon, Jul 04, 2016 at 10:22:04PM +0530, Malith Yapa wrote: >> >> > > Continuously polling registers with the PL2303 usb serial adapter >> >> > > eventually results in usb_subimit_urb failed with result -19 (ENODEV) >> >> > > but reconnects immediately. >> >> > > occurrences are random. >> >> > > tried with two different PL2303 devices with the same result. >> >> > >> >> > Sounds like a firmware issue, so not sure there's much we can do. >> >> > >> >> > Can you tell from the syslogs that the device is being disconnected and >> >> > re-enumerated? What registers are you polling? >> >> Ok. Thats fine with me as long as it reconnects. However since the >> device number keeps incrementing, I'm worried that it will fail >> sometime in the future. It failed a couple of times before (I think >> after reaching 255). I'm waiting for it to happen again to capture the >> syslog. Is there anyway i can force it to reconnect with the same >> id?(or come back to 0 after some time) what would be the maximum it >> can go upto? > > That would be 512 these days. > > The minor numbers are not reused until your application (or libmodbus) > releases them. The application should detect that the tty has been hung > up and close the tty device. > > Another thing you can try (to avoid the disconnect) is to verify that > you get the same behaviour using a different host controller (e.g. PC). > Try without any intermediate external hubs too. > > Good luck, > Johan Ok that makes sense. I think I've forgotten to close my modbus connection. On the disconnect issue, i don't have any external hubs. I'll try a different host, but if the minor numbers are reused my problem is largely solved :) Thanks a lot! Malith -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
