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Linux 3.14 USB serial

Posted on June 04, 2014 at 17:08

We have been using the STM32F205 product with a linux system to transfer data via the USB serial port emulation. On the linux side the usbserial module is used. The STM32 firmware uses the USB FS device library 3.3.0

This setup has been working perfectly with Linux 2.6.38.

After upgrading to Linux 3.14 we have started to see occasional lockups in serial data transfer MCU->Linux (USB IN direction) while the outbound transfer to the MCU continues to work.

Using a debugger on the STM32 I can see the MCU continues generating data, but data does not seem to be requested by the Linux USB host anymore.

Using Linux kernel debug output I could see that the URB submitted for receive data never return when the lockup occurs.

Apart from the updated Linux kernel no other system component has changed. Ths system is based on an intel Atom Z510 system-on-a-chip.

Any ideas how to solve this are greatly appreciated. Thanks a lot.