From: Nicholas Piggin <npiggin@gmail.com>
To: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
mpe@ellerman.id.au, benh@kernel.crashing.org,
ego@linux.vnet.ibm.com, huntbag@linux.vnet.ibm.com
Subject: Re: [RFC PATCH 3/3] cpuidle/powernv: Conditionally save-restore sprs using opal
Date: Fri, 3 Aug 2018 00:05:47 +1000 [thread overview]
Message-ID: <20180803000547.08a37175@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20180802045132.12432-4-akshay.adiga@linux.vnet.ibm.com>
On Thu, 2 Aug 2018 10:21:32 +0530
Akshay Adiga <akshay.adiga@linux.vnet.ibm.com> wrote:
> From: Abhishek Goel <huntbag@linux.vnet.ibm.com>
>
> If a state has "opal-supported" compat flag in device-tree, an opal call
> needs to be made during the entry and exit of the stop state. This patch
> passes a hint to the power9_idle_stop and power9_offline_stop.
>
> This patch moves the saving and restoring of sprs for P9 cpuidle
> from kernel to opal. This patch still uses existing code to detect
> first thread in core.
> In an attempt to make the powernv idle code backward compatible,
> and to some extent forward compatible, add support for pre-stop entry
> and post-stop exit actions in OPAL. If a kernel knows about this
> opal call, then just a firmware supporting newer hardware is required,
> instead of waiting for kernel updates.
Still think we should make these do-everything calls. Including
executing nap/stop instructions, restoring timebase, possibly even
saving and restoring SLB (although a return code could be used to
tell the kernel to do that maybe if performance advantage is enough).
I haven't had a lot of time to go through it, I'm working on moving
~all of idle_book3s.S to C code, I'd like to do that before this
OPAL idle driver if possible.
A minor thing I just noticed, you don't have to allocate the opal
spr save space in Linux, just do it all in OPAL.
Thanks,
Nick
next prev parent reply other threads:[~2018-08-02 14:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-02 4:51 [RFC PATCH 0/3] New device-tree format and Opal based idle save-restore Akshay Adiga
2018-08-02 4:51 ` [RFC PATCH 1/3] cpuidle/powernv: Add support for states with ibm,cpuidle-state-v1 Akshay Adiga
2018-08-02 4:51 ` [RFC PATCH 2/3] powernv/cpuidle: Pass pointers instead of values to stop loop Akshay Adiga
2018-08-02 4:51 ` [RFC PATCH 3/3] cpuidle/powernv: Conditionally save-restore sprs using opal Akshay Adiga
2018-08-02 14:05 ` Nicholas Piggin [this message]
2018-08-08 15:41 ` Gautham R Shenoy
2018-08-11 5:54 ` Nicholas Piggin
2018-08-07 12:15 ` [RFC PATCH 0/3] New device-tree format and Opal based idle save-restore Michael Ellerman
2018-08-08 6:02 ` Gautham R Shenoy
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