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Date: Thu, 13 Oct 2016 16:53:57 +0530 From: Gautham R Shenoy <ego@...ux.vnet.ibm.com> To: Stewart Smith <stewart@...ux.vnet.ibm.com> Cc: Gautham R Shenoy <ego@...ux.vnet.ibm.com>, Balbir Singh <bsingharora@...il.com>, Michael Ellerman <mpe@...erman.id.au>, "skiboot@...ts.ozlabs.org" <skiboot@...ts.ozlabs.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Paul Mackerras <paulus@...ba.org>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Daniel Lezcano <daniel.lezcano@...aro.org>, Michael Neuling <mikey@...ling.org>, Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>, "Shreyas B. Prabhu" <shreyasbp@...il.com>, Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org Subject: Re: [PATCH 2/2] powernv: Pass PSSCR value and mask to power9_idle_stop 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.
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