acrn-kernel/arch/mips/sibyte
Ralf Baechle a904f74785 [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>
2006-03-18 16:59:30 +00:00
..
bcm1480 [MIPS] Fix compiler warnings in arch/mips/sibyte/bcm1480/irq.c 2006-02-21 16:58:23 +00:00
cfe [MIPS] SMP: Fix initialization order bug. 2006-02-27 17:30:36 +00:00
sb1250 [MIPS] Sibyte: Fix race in sb1250_gettimeoffset(). 2006-03-18 16:59:30 +00:00
swarm [MIPS] Sibyte: Fix race in sb1250_gettimeoffset(). 2006-03-18 16:59:30 +00:00
Kconfig [MIPS] Sibyte: Config option names shouldn't be prefixed with CONFIG_ 2006-02-21 16:58:23 +00:00