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

Message ID 20191206191526.26543-1-desnesn@linux.ibm.com
State New
Headers show
Series selftests/powerpc: enable performance alerts when freezing counters on cycles_with_freeze_test selftest | expand


Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (567dea0e848944848650d7fd27699e2de5d49353)
snowpatch_ozlabs/build-ppc64le success Build succeeded
snowpatch_ozlabs/build-ppc64be success Build succeeded
snowpatch_ozlabs/build-ppc64e success Build succeeded
snowpatch_ozlabs/build-pmac32 success Build succeeded
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 8 lines checked
snowpatch_ozlabs/needsstable warning Please consider tagging this patch for stable!

Commit Message

Desnes Augusto Nunes do Rosario Dec. 6, 2019, 7:15 p.m. UTC
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(-)
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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;
-		mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_FC);
+		mtspr(SPRN_MMCR0, (mfspr(SPRN_MMCR0) & ~MMCR0_FC) | MMCR0_PMAE);