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| author | Ralf Baechle <ralf@linux-mips.org> | 2006-03-15 00:03:29 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2006-03-18 16:59:30 +0000 |
| commit | a904f7478561464f9fe74929b81fec237b6ff4c3 (patch) | |
| tree | 6018ab25ea391aad0f4f33f0613e2b9fdbe36637 /include/asm-mips/sibyte | |
| parent | 4308cb16286c96d980570cc5319173b524220c06 (diff) | |
| download | op-kernel-dev-a904f7478561464f9fe74929b81fec237b6ff4c3.zip op-kernel-dev-a904f7478561464f9fe74929b81fec237b6ff4c3.tar.gz | |
[MIPS] Sibyte: Fix race in sb1250_gettimeoffset().
From Dave Johnson <djohnson+linuxmips@sw.starentnetworks.com>:
sb1250_gettimeoffset() simply reads the current cpu 0 timer remaining
value, however once this counter reaches 0 and the interrupt is raised,
it immediately resets and begins to count down again.
If sb1250_gettimeoffset() is called on cpu 1 via do_gettimeofday() after
the timer has reset but prior to cpu 0 processing the interrupt and
taking write_seqlock() in timer_interrupt() it will return a full value
(or close to it) causing time to jump backwards 1ms. Once cpu 0 handles
the interrupt and timer_interrupt() gets far enough along it will jump
forward 1ms.
Fix this problem by implementing mips_hpt_*() on sb1250 using a spare
timer unrelated to the existing periodic interrupt timers. It runs at
1Mhz with a full 23bit counter. This eliminated the custom
do_gettimeoffset() for sb1250 and allowed use of the generic
fixed_rate_gettimeoffset() using mips_hpt_*() and timerhi/timerlo.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'include/asm-mips/sibyte')
| -rw-r--r-- | include/asm-mips/sibyte/sb1250.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-mips/sibyte/sb1250.h b/include/asm-mips/sibyte/sb1250.h index a474c29..b09e16c 100644 --- a/include/asm-mips/sibyte/sb1250.h +++ b/include/asm-mips/sibyte/sb1250.h @@ -45,8 +45,8 @@ extern unsigned int soc_type; extern unsigned int periph_rev; extern unsigned int zbbus_mhz; +extern void sb1250_hpt_setup(void); extern void sb1250_time_init(void); -extern unsigned long sb1250_gettimeoffset(void); extern void sb1250_mask_irq(int cpu, int irq); extern void sb1250_unmask_irq(int cpu, int irq); extern void sb1250_smp_finish(void); |
