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

Christoffer Dall christoffer.dall at linaro.org
Sun Dec 28 06:20:31 PST 2014

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 at chromium.org>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
Cc: Olof Johansson <olof at lixom.net>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Marc Zyngier <marc.zyngier at arm.com>
Cc: Yingjoe Chen <yingjoe.chen at mediatek.com>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
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;

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