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author | Al Cooper <alcooperx@gmail.com> | 2011-11-08 09:59:01 -0500 |
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committer | Ralf Baechle <ralf@linux-mips.org> | 2011-11-08 17:59:22 +0000 |
commit | 4f1a1eb530071c39fb239fd26c912a64284b1408 (patch) | |
tree | e4b00b9dab468604f97e2fbe1585ba0e87f37991 /arch/mips/include/asm/unistd.h | |
parent | e63fb7a9dae820b3ff6754f794fd713f83e32fff (diff) | |
download | op-kernel-dev-4f1a1eb530071c39fb239fd26c912a64284b1408.zip op-kernel-dev-4f1a1eb530071c39fb239fd26c912a64284b1408.tar.gz |
MIPS: Kernel hangs occasionally during boot.
The Kernel hangs occasionally during boot after "Calibrating delay loop..".
This is caused by the c0_compare_int_usable() routine in cevt-r4k.c
returning false which causes the system to disable the timer and hang later.
The false return happens because the routine is using a series of four calls
to irq_disable_hazard() as a delay while it waits for the timer changes to
propagate to the cp0 cause register. On newer MIPS cores, like the 74K, the
series of irq_disable_hazard() calls turn into ehb instructions and can take
as little as a few clock ticks for all 4 instructions. This is not enough of
a delay, so the routine thinks the timer is not working. This fix uses up
to a max number of cycle counter ticks for the delay and uses
back_to_back_c0_hazard() instead of irq_disable_hazard() to handle the
hazard condition between cp0 writes and cp0 reads.
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2911/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm/unistd.h')
0 files changed, 0 insertions, 0 deletions