From 0b46b8a718c6e90910a1b1b0fe797be3c167e186 Mon Sep 17 00:00:00 2001 From: Sonny Rao Date: Sun, 23 Nov 2014 23:02:44 -0800 Subject: 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 Acked-by: Catalin Marinas Acked-by: Daniel Lezcano Signed-off-by: Olof Johansson --- drivers/clocksource/arm_arch_timer.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/clocksource') 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; -- cgit v1.2.3