linux-kernel - Re: [PATCH v6 00/18] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s)

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Message-ID: <20191101123359.GG27141@pdeschrijver-desktop.Nvidia.com>
Date:   Fri, 1 Nov 2019 14:33:59 +0200
From:   Peter De Schrijver <pdeschrijver@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>
CC:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Daniel Lezcano" <daniel.lezcano@...aro.org>,
        <linux-pm@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 00/18] Consolidate and improve NVIDIA Tegra CPUIDLE
 driver(s)

On Tue, Oct 29, 2019 at 03:47:56AM +0300, Dmitry Osipenko wrote:
..

> >>>> It would be useful to switch the power state terminology to the one used
> >>>> for later chips:
> >>>>
> >>>> LP0 becomes SC7
> >>>> LP1 becomes C1
> >>>> LP2 becomes CC7
> >>>>
> >>>> Meaning of these states is as follows
> >>>>
> >>>> C is a core state:
> >>>>
> >>>> C1 clock gating
> >>>> C2 not defined
> >>>> C3 not defined
> >>>> C4 not defined
> >>>> C5 not defined
> >>>> C6 not defined for ARM cores
> >>>> C7 power-gating
> >>>>
> >>>> CC is a CPU cluster C state:
> >>>>
> >>>> CC1 cluster clock gated
> >>>> CC2 not defined
> >>>> CC3 fmax@...n: not used prior to Tegra186
> >>>> CC4: cluster retention: no longer supported
> >>>> CC5: not defined
> >>>> CC6: cluster power gating
> >>>> CC7: cluster rail gating
> >>>>
> >>>> SC is a System C state:
> >>>>
> >>>> SC1: not defined
> >>>> SC2: not defined
> >>>> SC3: not defined
> >>>> SC4: not defined
> >>>> SC5: not defined
> >>>> SC6: not defined
> >>>> SC7: VDD_SOC off
> >>>
> >>> Hello Peter,
> >>>
> >>> But new "drivers/cpuidle/cpuidle-tegra.c" uses exactly that terminology,
> >>> please see "cpuidle: Refactor and move NVIDIA Tegra20 driver into
> >>> drivers/cpuidle/" and further patches. Am I missing something? Or do you
> >>> want the renaming to be a separate patch?
> >>>
> >>
> >> Or maybe you're suggesting to change the names everywhere and not only
> >> in the cpuidle driver? Please clarify :)
> > 
> > At least some of the variable and function names still say lp2?
> 
> The cpuidle driver uses LP2 terminology for everything that comes from
> the external arch / firmware includes. But it says CC6 for everything
> that is internal to the driver. So yes, there is a bit of new/old
> terminology mixing in the code.
> 
> The arch code / PMC driver / TF firmware are all saying LP2. The LP2
> naming is also a part of the device-tree binding.
> 
> It will be a lot of mess to rename the mach-tegra/pm.c code. I guess
> eventually it could be moved to drivers/soc/, so maybe it will be better
> to postpone the renaming until then?

Or maybe add a comment somewhere indicating:

LP2 = CC6
LP1 = C1
LP0 = SC7

TF predates the new naming, so that may make some sense.

Peter.