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authorSonny Rao <sonnyrao@chromium.org>2014-11-24 10:02:44 +0300
committerOlof Johansson <olof@lixom.net>2014-12-05 10:30:26 +0300
commit0b46b8a718c6e90910a1b1b0fe797be3c167e186 (patch)
treeeca0d7cd13798df4bc81afe88f9686b9a3e1aaa6 /drivers/clocksource/arm_arch_timer.c
parentf114040e3ea6e07372334ade75d1ee0775c355e1 (diff)
downloadlinux-0b46b8a718c6e90910a1b1b0fe797be3c167e186.tar.xz
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/arm_arch_timer.c')
-rw-r--r--drivers/clocksource/arm_arch_timer.c5
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;