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Date:   Mon, 29 May 2023 09:08:48 -0700
From:   Bjorn Andersson <andersson@kernel.org>
To:     Ulf Hansson <ulf.hansson@linaro.org>
Cc:     Maulik Shah <quic_mkshah@quicinc.com>, dianders@chromium.org,
        swboyd@chromium.org, wingers@google.com,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, sudeep.holla@arm.com,
        jwerner@chromium.org, quic_lsrao@quicinc.com,
        quic_rjendra@quicinc.com
Subject: Re: [PATCH v4 0/3] Use PSCI OS initiated mode for sc7280
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On Mon, May 29, 2023 at 10:58:23AM +0200, Ulf Hansson wrote:
> On Thu, 25 May 2023 at 04:41, Bjorn Andersson <andersson@kernel.org> wrote:
> >
> > On Wed, May 24, 2023 at 11:56:28AM +0200, Ulf Hansson wrote:
> > > On Mon, 24 Apr 2023 at 13:09, Maulik Shah <quic_mkshah@quicinc.com> wrote:
> > > >
> > > > Changes in v4:
> > > > - Add missing s-o-b line and reviewed by in patch 1
> > > > - Address ulf's comments for error handling in patch 2
> > > >
> > > > Changes in v3:
> > > > - Add new change to provide helper function dt_idle_pd_remove_topology()
> > > > - Address ulf's comments for error handling
> > > > - Add reviewed by ulf for devicetree change
> > > >
> > > > Changes in v2:
> > > > - Add new change to Move enabling OSI mode after power domains creation
> > > > - Fix compatible string to domains-idle-states for cluster idle state.
> > > > - Update cover letter with some more details on OSI and PC mode
> > > >   comparision
> > > >
> > > > The dependency [2] is now merged in trustedfirmware project.
> > > >
> > > > Stats comparision between OSI and PC mode are captured at [3] with
> > > > usecase
> > > > details, where during multiple CPUs online the residency in cluster idle
> > > > state is better with OSI and also inline with single CPU mode. In PC
> > > > mode
> > > > with multiple CPUs cluster idle state residency is dropping compare to
> > > > single CPU mode.
> > > >
> > > > Recording of this meeting is also available at [4].
> > > >
> > > > This change adds power-domains for cpuidle states to use PSCI OS
> > > > initiated mode for sc7280.
> > > >
> > > > This change depends on external project changes [1] & [2] which are
> > > > under review/discussion to add PSCI os-initiated support in Arm Trusted
> > > > Firmware.
> > > >
> > > > I can update here once the dependency are in and change is ready to
> > > > merge.
> > > >
> > > > [1] https://review.trustedfirmware.org/q/topic:psci-osi
> > > > [2] https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/19487
> > > > [3] https://www.trustedfirmware.org/docs/PSCI-OS-initiated.pdf
> > > > [4] https://www.trustedfirmware.org/meetings/tf-a-technical-forum
> > > >
> > > > Maulik Shah (3):
> > > >   cpuidle: dt_idle_genpd: Add helper function to remove genpd topology
> > > >   cpuidle: psci: Move enabling OSI mode after power domains creation
> > > >   arm64: dts: qcom: sc7280: Add power-domains for cpuidle states
> > > >
> > > >  arch/arm64/boot/dts/qcom/sc7280.dtsi  | 98 ++++++++++++++++++++-------
> > > >  drivers/cpuidle/cpuidle-psci-domain.c | 39 ++++-------
> > > >  drivers/cpuidle/dt_idle_genpd.c       | 24 +++++++
> > > >  drivers/cpuidle/dt_idle_genpd.h       |  7 ++
> > > >  4 files changed, 117 insertions(+), 51 deletions(-)
> > > >
> > >
> > > Looks like this series has not been queued up yet. Note that patch1
> > > and patch2 are needed for stable kernels too. Moreover, patch3 (Qcom
> > > DTS change) is dependent on patch 1 and patch2.
> > >
> > > Therefore I suggest Bjorn to pick this up via the Qcom SoC tree.
> > > Bjorn, is that okay for you?
> > >
> >
> > Sorry, this fell between the chairs after you pointed me to it...
> >
> > I can certainly pick the 3 patches through my tree, but are they fixing
> > any current regressions, or is it just that we need the first two
> > patches to land before the 3rd patch?
> 
> I am not aware of any current regressions.
> 

Okay, that confirms my understanding. So not -rc material.

> >
> > I also presume the 3rd patch is only needed when paired with the new
> > ATF?
> 
> Patch3 is beneficial to use with a new TF-A, but works with an old
> TF-A too. Anyway, forget what I said about patch3 earlier, as that was
> just not the complete information.
> 
> The problem is that we can't be using a new TF-A (supporting both PSCI
> OSI and PC mode) without patch1 and patch2, unless we are using
> patch3.
> 
> Thus, I strongly suggest we tag patch1 and patch2 for stable kernels,
> to avoid any potential conflicts of TF-A versions that may be used.
> 

So you're suggesting that I pick them for v6.5 and add a Cc: stable?

An alternative would be that you take the cpuidle patches for v6.4-rc
and I pick the dt for v6.5 - given that the cpuidle patches actually
resolves a problem, while the dts just introduces "new functionality".

> >
> > Regards,
> > Bjorn
> 
> Did that make more sense?
> 

Yes, it's getting there :)

Thanks,
Bjorn

> Br
> Uffe