On Fri, Jan 16, 2015 at 2:53 AM, <malaa...@elisanet.fi> wrote: > 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?
Disable: CONFIG_USB_TI_CPPI41_DMA Enable: CONFIG_MUSB_PIO_ONLY > 2) Is there an easy way to create a custom dtb for the 3.18-bone kernels? Use the v3.19.x branch: https://github.com/RobertCNelson/dtb-rebuilder/tree/3.19.x Regards, -- Robert Nelson http://www.rcn-ee.com/ -- 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.
