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| author | Nicholas Piggin <npiggin@gmail.com> | 2017-07-20 11:53:22 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-08-04 12:52:26 +1000 |
| commit | 09539f9b123652e969894d6299ae0df2fe12cb5d (patch) | |
| tree | d48126ca0b6ab5d0a8e692deeaa52fb960bc59a4 /arch/powerpc/kernel/idle_book3s.S | |
| parent | f29bb7861a5107cc1afbf5a565c3109aa88d5984 (diff) | |
| download | lwn-09539f9b123652e969894d6299ae0df2fe12cb5d.tar.gz lwn-09539f9b123652e969894d6299ae0df2fe12cb5d.zip | |
powerpc/perf: POWER9 PMU stops after idle workaround
POWER9 DD2 PMU can stop after a state-loss idle in some conditions.
A solution is to set then clear MMCRA[60] after wake from state-loss
idle. MMCRA[60] is a non-architected bit, see the user manual for
details.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/idle_book3s.S')
| -rw-r--r-- | arch/powerpc/kernel/idle_book3s.S | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 516ebef905c0..e6252c5a57a4 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -460,11 +460,17 @@ pnv_restore_hyp_resource_arch300: /* * Workaround for POWER9, if we lost resources, the ERAT * might have been mixed up and needs flushing. We also need - * to reload MMCR0 (see comment above). + * to reload MMCR0 (see comment above). We also need to set + * then clear bit 60 in MMCRA to ensure the PMU starts running. */ blt cr3,1f PPC_INVALIDATE_ERAT ld r1,PACAR1(r13) + mfspr r4,SPRN_MMCRA + ori r4,r4,(1 << (63-60)) + mtspr SPRN_MMCRA,r4 + xori r4,r4,(1 << (63-60)) + mtspr SPRN_MMCRA,r4 ld r4,_MMCR0(r1) mtspr SPRN_MMCR0,r4 1: |