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Subject: Re: [PATCH v2 0/3] Power10 basic energy management
To:     Nicholas Piggin <npiggin@gmail.com>, 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,
        ravi.bangoria@linux.ibm.com, svaidy@linux.ibm.com
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From:   Pratik Sampat <psampat@linux.ibm.com>
Message-ID: <cce3c51b-8614-5f4b-89ea-be5872bdcd7c@linux.ibm.com>
Date:   Mon, 13 Jul 2020 23:57:14 +0530
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On 13/07/20 10:20 pm, Nicholas Piggin wrote:
> Excerpts from Pratik Sampat's message of July 13, 2020 8:02 pm:
>> Thank you for your comments,
>>
>> On 13/07/20 10:53 am, 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
>>>
>>> Thanks,
>>> Nick
>> So if I understand this correctly, in powernv/idle.c where we check for
>> CPU_FTR_ARCH_300, we should rather be making a pvr_version_is(PVR_POWER9)
>> check instead?
>>
>> Of course, the P10 PVR and its relevant checks will have to be added then too.
> Yes I think so, unfortunately.
>
> Thanks,
> Nick

Sure, I'll add these checks in.

Thanks,
Pratik