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| author | Sonny Rao <sonnyrao@chromium.org> | 2014-11-23 23:02:44 -0800 |
|---|---|---|
| committer | Olof Johansson <olof@lixom.net> | 2014-12-04 23:30:26 -0800 |
| commit | 0b46b8a718c6e90910a1b1b0fe797be3c167e186 (patch) | |
| tree | eca0d7cd13798df4bc81afe88f9686b9a3e1aaa6 /drivers/clocksource | |
| parent | f114040e3ea6e07372334ade75d1ee0775c355e1 (diff) | |
| download | blackbird-op-linux-0b46b8a718c6e90910a1b1b0fe797be3c167e186.tar.gz blackbird-op-linux-0b46b8a718c6e90910a1b1b0fe797be3c167e186.zip | |
clocksource: arch_timer: Fix code to use physical timers when requested
This is a bug fix for using physical arch timers when
the arch_timer_use_virtual boolean is false. It restores the
arch_counter_get_cntpct() function after removal in
0d651e4e "clocksource: arch_timer: use virtual counters"
We need this on certain ARMv7 systems which are architected like this:
* The firmware doesn't know and doesn't care about hypervisor mode and
we don't want to add the complexity of hypervisor there.
* The firmware isn't involved in SMP bringup or resume.
* The ARCH timer come up with an uninitialized offset between the
virtual and physical counters. Each core gets a different random
offset.
* The device boots in "Secure SVC" mode.
* Nothing has touched the reset value of CNTHCTL.PL1PCEN or
CNTHCTL.PL1PCTEN (both default to 1 at reset)
One example of such as system is RK3288 where it is much simpler to
use the physical counter since there's nobody managing the offset and
each time a core goes down and comes back up it will get reinitialized
to some other random value.
Fixes: 0d651e4e65e9 ("clocksource: arch_timer: use virtual counters")
Cc: stable@vger.kernel.org
Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'drivers/clocksource')
| -rw-r--r-- | drivers/clocksource/arm_arch_timer.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 2133f9d59d06..55256e4fb641 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -462,7 +462,10 @@ static void __init arch_counter_register(unsigned type) /* Register the CP15 based counter if we have one */ if (type & ARCH_CP15_TIMER) { - arch_timer_read_counter = arch_counter_get_cntvct; + if (arch_timer_use_virtual) + arch_timer_read_counter = arch_counter_get_cntvct; + else + arch_timer_read_counter = arch_counter_get_cntpct; } else { arch_timer_read_counter = arch_counter_get_cntvct_mem; |
