[PATCH] clocksource: arch_timer: Fix arm64 platforms not booting

From: Christoffer Dall
Date: Sun Dec 28 2014 - 09:20:41 EST

Commit 0b46b8a718c6e ("clocksource: arch_timer: Fix code to...") fixes
timer issues with certain ARMv7 platforms, but unfortunately breaks
arm64 platforms with hyp mode (EL2) enabled.

The commit only sets arch_timer_use_virtual to false under CONFIG_ARM,
but forgets that the config variable is also set in other code paths
(actually, right underneath the check in the patch) with detrimental
consequences as we've now introduced a direct early call to BUG() on
practically all arm64 platforms.

One could argue that this code could be refactored to use different
variables for checking which *timer* to use and which *counter* to use,
which seems to be the desired difference between ARM and arm64 in this
case, but this approach fixes an urgent issue for now.

Cc: Sonny Rao <sonnyrao@xxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Olof Johansson <olof@xxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
This was apparently already discovered by Yingjoe Chen in this thread
https://lkml.org/lkml/2014/11/24/41 and Catalin recommended a similar

drivers/clocksource/arm_arch_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6a79fc4..095c177 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -462,7 +462,7 @@ static void __init arch_counter_register(unsigned type)

/* Register the CP15 based counter if we have one */
if (type & ARCH_CP15_TIMER) {
- if (arch_timer_use_virtual)
+ if (IS_ENABLED(CONFIG_ARM64) || arch_timer_use_virtual)
arch_timer_read_counter = arch_counter_get_cntvct;
arch_timer_read_counter = arch_counter_get_cntpct;

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/