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author | Huacai Chen <chenhc@lemote.com> | 2016-07-21 14:27:51 +0800 |
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committer | Ralf Baechle <ralf@linux-mips.org> | 2016-07-24 12:01:00 +0200 |
commit | 3ef06653987d4c4536b408321edf0e5caa2a317f (patch) | |
tree | 2ceef19d66fd2d029e5b3b64454d947eac807383 /arch/mips/mti-sead3 | |
parent | 07d69579e7fec27e371296d8ca9d6076fc401b5c (diff) | |
download | linux-3ef06653987d4c4536b408321edf0e5caa2a317f.tar.gz linux-3ef06653987d4c4536b408321edf0e5caa2a317f.tar.bz2 linux-3ef06653987d4c4536b408321edf0e5caa2a317f.zip |
MIPS: hpet: Increase HPET_MIN_PROG_DELTA and decrease HPET_MIN_CYCLES
At first, we prefer to use mips clockevent device, so we decrease the
rating of hpet clockevent device.
For hpet, if HPET_MIN_PROG_DELTA (minimum delta of hpet programming) is
too small and HPET_MIN_CYCLES (threshold of -ETIME checking) is too
large, then hpet_next_event() can easily return -ETIME. After commit
c6eb3f70d44828 ("hrtimer: Get rid of hrtimer softirq") this will cause
a RCU stall.
So, HPET_MIN_PROG_DELTA must be sufficient that we don't re-trip the
-ETIME check -- if we do, we will return -ETIME, forward the next event
time, try to set it, return -ETIME again, and basically lock the system
up. Meanwhile, HPET_MIN_CYCLES doesn't need to be too large, 16 cycles
is enough.
This solution is similar to commit f9eccf24615672 ("clocksource/drivers
/vt8500: Increase the minimum delta").
By the way, this patch ensures hpet count/compare to be 32-bit long.
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J . Hill <Steven.Hill@imgtec.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13819/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/mti-sead3')
0 files changed, 0 insertions, 0 deletions