Hi, I have a simple C program which writes something to a serial port and then reads an answer, every 5 ms or so. I'm using an FTDI USB-to-RS232 adapter connected to BBB at 115200 bps. In 3.8.13-bone63 this works fine, but there are some reasons I need to use a later kernel. I upgraded to the 3.14.22-ti-r31 kernel, where my program freezes the user space completely after a couple of seconds. Unplugging the USB adapter makes everything run again (but of course my program closes since the serial port is no longer there). Nothing special in dmesg. I then upgraded to 3.14.26-ti-r43, where the problem is slightly different, appearing after several minutes to an hour or so, and not freezing completely, making everything just incredibly slow (softirq's use about 70 % of CPU time according to top). Closing my program brings everything back to normal. Then I tried 3.18.2-bone1, where it works again correctly.
I see that bone-kernels have DMA disabled in USB, but I also tried use_dma=0 module parameter with 3.14.26-ti-r43 and it didn't help. I'd use 3.18.2, but unfortunately dtb-rebuilder doesn't have a branch for that kernel, and I need to modify the GPIO's a little. The .dtb-file for 3.14.26 doesn't boot with 3.18.2. So, 1) Is there something I could try to make it work on 3.14-ti kernels? 2) Is there an easy way to create a custom dtb for the 3.18-bone kernels? Thanks, Matti -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
