Hello everybody,
after nailing down a few USB and FAT related bugs we had USB running stable on i.MX31, but suddenly the current mainline code behaves strangely again:
Repeating simple calls like "usb read 80800000 0 1000" will reliably hard hang the system after 3...5 calls.
The problem can be avoided by switching off the instruction cache (using the "icache off" command).
Trying to track down this problem it turns out that somehow the ELF_RELOC patches seem to be responsible for it. I have a source tree that works perfectly fine, with I-caches on, and after cherry-picking the following commits from the elf_reloc branch the problem appears:
92d5ecb 2010-10-13 10:10:21 arm: implement ELF relocations bafe743 2010-10-13 10:12:52 arm1136, qong: add support for ELF relocations
However, we cannot find a real cause in the modified code.
Here my request for help:
- Has anybody experienced similar problems?
- Did your tests of the elf_reloc code include any thorough testing of USB mass storage devices?
- If you have any suitable hardware around, could you please run a few such tests (as mentioned above, a simple "usb read <addr> 0 1000", repeated 5 times or so, should be sufficient. If you want to be sure, increase the block count and repeat more often.
All ideas welcome. Thanks a lot in advance.
Best regards,
Wolfgang Denk