On 12/23/14 19:26, kott wrote:
Hello -
I am seeing this fault when i plugin a external usb device, and was
wondering if this indicates DMA/Cache coherency problem
_ehci_append_qh: 0xf3dd2300 to 0xf3dc3c00
Kernel page fault with the following non-sleepable locks held:
exclusive sleep mutex ehci0 (usb_def_mtx) r = 0 (0xc73ece74) locked @
exclusive sleep mutex USB device mutex (USB device mutex) r = 0 (0xc73da850)
locked @ /sys/dev/usb/usb_transfer.c

Stopped at      usb_pc_cpu_flush+0xc:   ldr     r2, [r0, #0x018]



The flush is supposed to call some other functions which write the memory cache to RAM. It should not panic like that. Can you get the complete backtrace. I guess that some memory content might have been lost due to missing or wrong cache sync operations. What is the value of "r0" ?


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