[PATCH] selftests/powerpc: enable performance alerts when freezing counters on cycles_with_freeze_test selftest

[PATCH] selftests/powerpc: enable performance alerts when freezing counters on cycles_with_freeze_test selftest

[Desnes A. Nunes do Rosario]

From: Gustavo Romero <gromero@linux.ibm.com>

When disabling freezing counters by setting MMCR0 FC bit to 0, the MMCR0
PMAE bit must also be enabled if a Performance Monitor Alert (and the cor-
responding Performance Monitor Interrupt) is still desired to be received
when an enabled condition or event occurs.

This is the case of the cycles_with_freeze_test selftest, since the test
disables the MMCR0 PMAE due to the usage of PMU to trigger EBBs. This can
make the test loop up to the point of being killed by the test harness
timeout (2500 ms), since no other ebb event will happen because the MMCR0
PMAE bit is disabled, and thus, no more increments to ebb_count occur.

Fixes: 3752e453f6bafd7 ("selftests/powerpc: Add tests of PMU EBBs")
Signed-off-by: Gustavo Romero <gromero@linux.ibm.com>
[desnesn: Only set MMCR0_PMAE when disabling MMCR0_FC, reflow comment]
Signed-off-by: Desnes A. Nunes do Rosario <desnesn@linux.ibm.com>
---
 .../testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c b/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c
index dcd351d20328..46b5a7d46c60 100644
--- a/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c
+++ b/tools/testing/selftests/powerpc/pmu/ebb/cycles_with_freeze_test.c
@@ -81,7 +81,7 @@ int cycles_with_freeze(void)
 	{
 		counters_frozen = false;
 		mb();
-		mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
+		mtspr(SPRN_MMCR0, (mfspr(SPRN_MMCR0) & ~MMCR0_FC) | MMCR0_PMAE);
 
 		FAIL_IF(core_busy_loop());
 
-- 
2.21.0