Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 09539f9b authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

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: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatarMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
Reviewed-by: default avatarVaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent f29bb786

arch/powerpc/kernel/idle_book3s.S

+7 −1
Original line number Diff line number Diff line
@@ -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: