From: Gautham R Shenoy <ego@linux•vnet.ibm.com>
To: Stewart Smith <stewart@linux•vnet.ibm.com>
Cc: Gautham R Shenoy <ego@linux•vnet.ibm.com>,
Balbir Singh <bsingharora@gmail•com>,
Michael Ellerman <mpe@ellerman•id.au>,
"skiboot@lists•ozlabs.org" <skiboot@lists•ozlabs.org>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
"Rafael J. Wysocki" <rjw@rjwysocki•net>,
Daniel Lezcano <daniel.lezcano@linaro•org>,
Michael Neuling <mikey@neuling•org>,
Vaidyanathan Srinivasan <svaidy@linux•vnet.ibm.com>,
"Shreyas B. Prabhu" <shreyasbp@gmail•com>,
Shilpasri G Bhat <shilpa.bhat@linux•vnet.ibm.com>,
linuxppc-dev@lists•ozlabs.org, linux-kernel@vger•kernel.org,
linux-pm@vger•kernel.org
Subject: Re: [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop
Date: Thu, 13 Oct 2016 16:53:57 +0530 [thread overview]
Message-ID: <20161013112357.GB9002@in.ibm.com> (raw)
In-Reply-To: <87lgxuf7tk.fsf@linux.vnet.ibm.com>
Hi Stewart,
On Wed, Oct 12, 2016 at 04:35:35PM +1100, Stewart Smith wrote:
>
> What if we just treat the 0xF state from firmware as special and set it
> to DEFAULT_PSSCR_MASK in that case? That deals with old skiboot, new
> kernel, and sets a pretty small special case that's easy to track into
> the future as something we should watch out for.
Yes, that will work. I will use this approach in the next version.
>
> Additionally, if we make skiboot set sane values in ~DEFAULT_PSSCR_MASK
> for valid fields in PSSCR on boot/(also kexec?), then
> we should end up in a situation where everything works with everything
> (even if you don't get the best power saving). Specifically, new
> skiboot, old kernel... but it looks like there's nothing currently
> missing there
No we're not missing much there. From the code of the old kernel, I
see that if we pass the psscr_val instead of just the RL to
power9_idle_stop(), we end up saving all the SPRs in
power_enter_stop() even if the psscr_val didn't correspond to a deep
idle state.
But that should be ok.
>
> Should this patch also have Fixes: 3005c597ba4 and CC to stable?
Yes, thanks for pointing it out. I shall mark the next version to
stable.
>
> --
> Stewart Smith
> OPAL Architect, IBM.
--
Thanks and Regards
gautham.
prev parent reply other threads:[~2016-10-13 11:24 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-29 7:05 [PATCH 0/2] powernv:stop: Use psscr_val,mask provided by firmware Gautham R. Shenoy
2016-09-29 7:05 ` [PATCH 1/2] powernv:idle: Add IDLE_STATE_ENTER_SEQ_NORET macro Gautham R. Shenoy
2016-09-29 7:05 ` [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop Gautham R. Shenoy
2016-10-04 10:32 ` Michael Ellerman
2016-10-04 11:33 ` Balbir Singh
2016-10-07 7:20 ` Gautham R Shenoy
2016-10-12 5:35 ` Stewart Smith
2016-10-13 11:23 ` Gautham R Shenoy [this message]
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