linux-kernel - Re: [PATCH v2 0/3] Power10 basic energy management

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Date:   Tue, 14 Jul 2020 02:58:53 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     ego@...ux.vnet.ibm.com
Cc:     benh@...nel.crashing.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, mikey@...ling.org,
        mpe@...erman.id.au, paulus@...ba.org, pratik.r.sampat@...il.com,
        Pratik Rajesh Sampat <psampat@...ux.ibm.com>,
        ravi.bangoria@...ux.ibm.com, svaidy@...ux.ibm.com
Subject: Re: [PATCH v2 0/3] Power10 basic energy management

Excerpts from Gautham R Shenoy's message of July 13, 2020 8:48 pm:
> On Mon, Jul 13, 2020 at 03:23:21PM +1000, Nicholas Piggin wrote:
>> Excerpts from Pratik Rajesh Sampat's message of July 10, 2020 3:22 pm:
>> > Changelog v1 --> v2:
>> > 1. Save-restore DAWR and DAWRX unconditionally as they are lost in
>> > shallow idle states too
>> > 2. Rename pnv_first_spr_loss_level to pnv_first_fullstate_loss_level to
>> > correct naming terminology
>> > 
>> > Pratik Rajesh Sampat (3):
>> >   powerpc/powernv/idle: Exclude mfspr on HID1,4,5 on P9 and above
>> >   powerpc/powernv/idle: save-restore DAWR0,DAWRX0 for P10
>> >   powerpc/powernv/idle: Rename pnv_first_spr_loss_level variable
>> > 
>> >  arch/powerpc/platforms/powernv/idle.c | 34 +++++++++++++++++----------
>> >  1 file changed, 22 insertions(+), 12 deletions(-)
>> 
>> These look okay to me, but the CPU_FTR_ARCH_300 test for 
>> pnv_power9_idle_init() is actually wrong, it should be a PVR test 
>> because idle is not completely architected (not even shallow stop 
>> states, unfortunately).
>> 
>> It doesn't look like we support POWER10 idle correctly yet, and on older
>> kernels it wouldn't work even if we fixed newer, so ideally the PVR 
>> check would be backported as a fix in the front of the series.
>> 
>> Sadly, we have no OPAL idle driver yet. Hopefully we will before the
>> next processor shows up :P
> 
> Abhishek posted a version recently :
> https://patchwork.ozlabs.org/project/skiboot/patch/20200706043533.76539-1-huntbag@linux.vnet.ibm.com/

Yep, I saw that. Still keen to get it working, just had other priorities 
in the short term. We'll need to do this OPAL v4 thing for it.

Thanks,
Nick