/dev/ACM0 long turnaround time waiting on EAGAIN - Raspberry Pi Forums
rtfm's welcome.
hi all,
last few years i've been running pair of raspberrypi model b's temperature collection. use canakit uk1104 http://www.canakit.com/4-port-usb-relay-controller.html usb adc/relay board along simple custom signal conditioner thermistors i'm using. has been running reliably until ~ mid february when did pretty standard apt-get update/upgrade. i'm assuming 3.18 kernel or device change of kind has occurred.
systems continued work frequent (60%) random failure in serial communications. have isolated problem section of code sends , receives ascii commands uk1104. example:
sending:
ch2.getanalog\n
returns (more or less):
ch2.getanalog\n470\n\n::\n
seeing frequent random error 11 eagain - device temporarily unavailable. error occurred after command write , usleep(10000) (10 ms) during subsequent read. port opened @ 115kbps.
ended checking error , waiting - workaround. turnaround time enormous , 1 second timeout (retrying read every 10ms) between writes , reads port ( < 0.5% of time) continues report temporarily unavailable , routine fails.
relevant details below.
dmesg:
[ 3.494660] usb 1-1.3: new full-speed usb device number 4 using dwc_otg
[ 3.656055] usb 1-1.3: new usb device found, idvendor=04d8, idproduct=fc73
[ 3.667461] usb 1-1.3: new usb device strings: mfr=1, product=2, serialnumber=0
[ 3.682389] usb 1-1.3: product: cana kit uk1104
[ 3.691865] usb 1-1.3: manufacturer: canakit.com
[ 4.458744] udevd[159]: starting version 175
[ 5.909295] cdc_acm 1-1.3:1.0: device cannot calls on own. not modem.
[ 6.021221] cdc_acm 1-1.3:1.0: ttyacm0: usb acm device
[ 6.157936] usbcore: registered new interface driver cdc_acm
[ 6.295214] cdc_acm: usb abstract control model driver usb modems , isdn adapters
ijeffsc@raspberrypi ~ $ uname -a
linux raspberrypi 3.18.7+ #755 preempt thu feb 12 17:14:31 gmt 2015 armv6l gnu/linux
hi all,
last few years i've been running pair of raspberrypi model b's temperature collection. use canakit uk1104 http://www.canakit.com/4-port-usb-relay-controller.html usb adc/relay board along simple custom signal conditioner thermistors i'm using. has been running reliably until ~ mid february when did pretty standard apt-get update/upgrade. i'm assuming 3.18 kernel or device change of kind has occurred.
systems continued work frequent (60%) random failure in serial communications. have isolated problem section of code sends , receives ascii commands uk1104. example:
sending:
ch2.getanalog\n
returns (more or less):
ch2.getanalog\n470\n\n::\n
seeing frequent random error 11 eagain - device temporarily unavailable. error occurred after command write , usleep(10000) (10 ms) during subsequent read. port opened @ 115kbps.
ended checking error , waiting - workaround. turnaround time enormous , 1 second timeout (retrying read every 10ms) between writes , reads port ( < 0.5% of time) continues report temporarily unavailable , routine fails.
relevant details below.
dmesg:
[ 3.494660] usb 1-1.3: new full-speed usb device number 4 using dwc_otg
[ 3.656055] usb 1-1.3: new usb device found, idvendor=04d8, idproduct=fc73
[ 3.667461] usb 1-1.3: new usb device strings: mfr=1, product=2, serialnumber=0
[ 3.682389] usb 1-1.3: product: cana kit uk1104
[ 3.691865] usb 1-1.3: manufacturer: canakit.com
[ 4.458744] udevd[159]: starting version 175
[ 5.909295] cdc_acm 1-1.3:1.0: device cannot calls on own. not modem.
[ 6.021221] cdc_acm 1-1.3:1.0: ttyacm0: usb acm device
[ 6.157936] usbcore: registered new interface driver cdc_acm
[ 6.295214] cdc_acm: usb abstract control model driver usb modems , isdn adapters
ijeffsc@raspberrypi ~ $ uname -a
linux raspberrypi 3.18.7+ #755 preempt thu feb 12 17:14:31 gmt 2015 armv6l gnu/linux
hi all,
see 70 or folks have reviewed post without comment. i'm working on code snippet can posted , demonstrates behaviour i'm seeing. in mean time i'm still digging around forums. code used usb serial io based on snippets found in thread: viewtopic.php?f=33&t=7500.
turnaround slow expected able reproduce problem in minicom unable to. i'm suspecting error in code tolerated in previous kernel isn't in one.
has else seen usb serial (ttysacm0) problems arise after kernel upgrade?
see 70 or folks have reviewed post without comment. i'm working on code snippet can posted , demonstrates behaviour i'm seeing. in mean time i'm still digging around forums. code used usb serial io based on snippets found in thread: viewtopic.php?f=33&t=7500.
turnaround slow expected able reproduce problem in minicom unable to. i'm suspecting error in code tolerated in previous kernel isn't in one.
has else seen usb serial (ttysacm0) problems arise after kernel upgrade?
raspberrypi
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