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USB Serial constructor blocking #53

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larsgk opened this issue Sep 2, 2013 · 4 comments
Closed

USB Serial constructor blocking #53

larsgk opened this issue Sep 2, 2013 · 4 comments
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component: usb

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@larsgk
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larsgk commented Sep 2, 2013

Because of a blocking connect function in USBDevice ( https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBDevice/USBDevice.cpp#L711 ) called from the USBCDC constructor ( https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBSerial/USBCDC.cpp#L34 ), instatiating USB Serial with nothing connected on the actual port blocks execution.

I tried just commenting the while loop out and everything seems to run fine (connect/disconnect and CDC/serial communication with a host computer.

Maybe this should be solved in a different way - but especially when running on battery on KL25Z, this is a problem (the blocking).
@larsgk
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larsgk commented Oct 25, 2013

Hi again,

I did some more research on this issue (that more than me seem to have - according to some entries on mbed.org).

There are several issues (all tested on FRDM-KL25Z):

  1. if you try to construct USBSerial with nothing connected to the USB Comm port, the program hangs in a forever loop here (I commented it out to be able to do battery/wireless operation - and this seems to work quite nicely.. the device can be switched on while connected or not .. reconnects work just fine, etc.):

https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBDevice/USBDevice.cpp#L711

  1. if you pull the plug while in a transfer, the program hangs in a forever "pending" loop here:

https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBDevice/USBDevice.cpp#L835

I am going to try to see if there is any way (maybe only for the FRDM-KL25Z board specifically) to detect if there is something connected to do a graceful startup/shutdown of the USB chain.

Also - if the code in USBDevice.cpp#L835 knows that it's pending for a long time (e.g. 20 checks..) then there should be a way to throw an exception (I know... not exception but C-style callbacks, etc.) up through the chain AS WELL as doing a graceful shutdown/reset of anything in the transfer buffer. The current mechanism leaves room for improvement at least :) - I am happy to contribute with my findings but please help me out a bit..we have to deliver 30 educational packages to a high-school soon.. based on this.

br
Lars

@larsgk
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larsgk commented Feb 18, 2014

I am wondering why the writable operation is not implemented to return something useful?

https://github.com/mbedmicro/mbed/blob/master/libraries/USBDevice/USBSerial/USBSerial.h#L99

@larsgk larsgk mentioned this issue Feb 18, 2014
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@amveeq amveeq mentioned this issue Aug 7, 2015
Closed
bridadan pushed a commit that referenced this issue Jun 21, 2016
@sg-
Merge pull request #53 from bridadan/circle-gcc-4_9
28334b0 
Make CircleCI install GCC ARM 4.9 instead of 5.x or 6.x
@ciarmcom
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ciarmcom commented Aug 1, 2016

ARM Internal Ref: IOTMORF-331

@sg- sg- added enhancement and removed mirrored labels Aug 12, 2016
@larsgk larsgk mentioned this issue Sep 28, 2016
Closed
hasnainvirk pushed a commit to hasnainvirk/mbed-os that referenced this issue Feb 12, 2017
Squashed 'features/nanostack/FEATURE_NANOSTACK/coap-service/' changes…
7dc2dc8 
… from a1982c1..e125164

e125164 Check secure session pointer in timer callback (ARMmbed#61)
f49e596 Update unit tests (ARMmbed#59)
6a5634a Support for multiple virtual services (ARMmbed#58)
7fe6b98 Remove yotta files (ARMmbed#57)
5c5c8fe Fix socket send return value overflow (ARMmbed#56)
0870d05 Update unit test stubs to match latest socket api (ARMmbed#55)
e687be8 Merge pull request ARMmbed#54 from ARMmbed/warn_fixes
b8fe613 updated unittests
8640d05 Compilation warnings fixed
eea83e5 Flag out entropy source addition (ARMmbed#53)
7d72eb4 Fix unittests (ARMmbed#52)
4a6991e Avoid referencing ns_msghdr_t::flags

git-subtree-dir: features/nanostack/FEATURE_NANOSTACK/coap-service
git-subtree-split: e125164
@devanlai devanlai mentioned this issue Mar 11, 2017
Merged
SeppoTakalo pushed a commit that referenced this issue Mar 16, 2017
Squashed 'features/FEATURE_COMMON_PAL/mbed-trace/' changes from 31e33…
c8a16cc 
…8c23..af5f59cd2

af5f59cd2 Add CMakeLists.txt to support PAL Tools (#61)
24e16e766 Fix header documentation (#58)
23ea8f51c Update README.md (#57)
99aaa6eef Provide environment-agnostic configuration macros. (#54)
da9eb9f3a Merge pull request #53 from ARMmbed/max_trace_level
0a51dcae8 Flash size can be limited by defining MBED_TRACE_MAX_LEVEL

git-subtree-dir: features/FEATURE_COMMON_PAL/mbed-trace
git-subtree-split: af5f59cd2cbac4064875be0c339da114d88fd5e1
@ghost
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ghost commented Oct 27, 2017

GitHib issue review: Closed due to inactivity. Please re-file if critical issues found.

@ghost ghost closed this as completed Oct 27, 2017
geky added a commit to geky/mbed that referenced this issue Aug 25, 2018
@geky
Merge pull request ARMmbed#53 from deepikabhavnani/dummy_read
2a1c923 
Checking for version, for OS master support
yossi2le pushed a commit to yossi2le/mbed-os that referenced this issue Jan 2, 2019
@LiyouZhou
Add bootloader support for UBLOX_C030_U201 (ARMmbed#53)
2bc92fc 
* Add support for UBLOX_C030_U201
geky pushed a commit to geky/mbed that referenced this issue Jan 17, 2019
@FreddieChopin
Add C++ guards to public headers
577d777 
Fixes ARMmbed#53
Fixes ARMmbed#32
linlingao added a commit to linlingao/mbed-os that referenced this issue Jul 12, 2019
@linlingao
Merge pull request ARMmbed#53 from linlingao/lp_ticker_bits
4bd5967 
Changed LP ticker count to 32 because the effective bitcount in Mbed …
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