From: Nicholas Piggin <npiggin@gmail.com>
To: benh@kernel.crashing.org, ego@linux.vnet.ibm.com,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
mikey@neuling.org, mpe@ellerman.id.au, paulus@samba.org,
pratik.r.sampat@gmail.com,
Pratik Rajesh Sampat <psampat@linux.ibm.com>,
ravi.bangoria@linux.ibm.com, svaidy@linux.ibm.com
Subject: Re: [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0, DAWRX0 for P10
Date: Mon, 13 Jul 2020 15:52:32 +1000 [thread overview]
Message-ID: <1594619458.45vrahx59w.astroid@bobo.none> (raw)
In-Reply-To: <20200710052207.12003-3-psampat@linux.ibm.com>
Excerpts from Pratik Rajesh Sampat's message of July 10, 2020 3:22 pm:
> Additional registers DAWR0, DAWRX0 may be lost on Power 10 for
> stop levels < 4.
> Therefore save the values of these SPRs before entering a "stop"
> state and restore their values on wakeup.
Hmm, where do you get this from? Documentation I see says DAWR is lost
on POWER9 but not P10.
Does idle thread even need to save DAWR, or does it get switched when
going to a thread that has a watchpoint set?
Thanks,
Nick
>
> Signed-off-by: Pratik Rajesh Sampat <psampat@linux.ibm.com>
> ---
> arch/powerpc/platforms/powernv/idle.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index 19d94d021357..f2e2a6a4c274 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -600,6 +600,8 @@ struct p9_sprs {
> u64 iamr;
> u64 amor;
> u64 uamor;
> + u64 dawr0;
> + u64 dawrx0;
> };
>
> static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
> @@ -687,6 +689,10 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
> sprs.iamr = mfspr(SPRN_IAMR);
> sprs.amor = mfspr(SPRN_AMOR);
> sprs.uamor = mfspr(SPRN_UAMOR);
> + if (cpu_has_feature(CPU_FTR_ARCH_31)) {
> + sprs.dawr0 = mfspr(SPRN_DAWR0);
> + sprs.dawrx0 = mfspr(SPRN_DAWRX0);
> + }
>
> srr1 = isa300_idle_stop_mayloss(psscr); /* go idle */
>
> @@ -710,6 +716,10 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on)
> mtspr(SPRN_IAMR, sprs.iamr);
> mtspr(SPRN_AMOR, sprs.amor);
> mtspr(SPRN_UAMOR, sprs.uamor);
> + if (cpu_has_feature(CPU_FTR_ARCH_31)) {
> + mtspr(SPRN_DAWR0, sprs.dawr0);
> + mtspr(SPRN_DAWRX0, sprs.dawrx0);
> + }
>
> /*
> * Workaround for POWER9 DD2.0, if we lost resources, the ERAT
> --
> 2.25.4
>
>
next prev parent reply other threads:[~2020-07-13 5:54 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 5:22 [PATCH v2 0/3] Power10 basic energy management Pratik Rajesh Sampat
2020-07-10 5:22 ` [PATCH v2 1/3] powerpc/powernv/idle: Exclude mfspr on HID1, 4, 5 on P9 and above Pratik Rajesh Sampat
2020-07-13 5:53 ` Nicholas Piggin
2020-07-10 5:22 ` [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0, DAWRX0 for P10 Pratik Rajesh Sampat
2020-07-13 5:52 ` Nicholas Piggin [this message]
2020-07-20 4:30 ` Ravi Bangoria
2020-07-20 4:24 ` [PATCH v2 2/3] powerpc/powernv/idle: save-restore DAWR0,DAWRX0 " Ravi Bangoria
2020-07-24 1:25 ` Michael Neuling
2020-07-24 6:34 ` Pratik Sampat
2020-07-10 5:22 ` [PATCH v2 3/3] powerpc/powernv/idle: Rename pnv_first_spr_loss_level variable Pratik Rajesh Sampat
2020-07-13 5:23 ` [PATCH v2 0/3] Power10 basic energy management Nicholas Piggin
2020-07-13 10:02 ` Pratik Sampat
2020-07-13 16:50 ` Nicholas Piggin
2020-07-13 18:27 ` Pratik Sampat
2020-07-13 10:48 ` Gautham R Shenoy
2020-07-13 16:58 ` Nicholas Piggin
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