linux-kernel - Re: [PATCH v1 07/17] cpufreq: tegra20: Use generic cpufreq-dt driver (Tegra30 supported now)

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Message-ID: <20191017023210.x5vavl542hdkrivw@vireshk-i7>
Date:   Thu, 17 Oct 2019 08:02:10 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Peter Geis <pgwipeout@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Nicolas Chauvet <kwizart@...il.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 07/17] cpufreq: tegra20: Use generic cpufreq-dt driver
 (Tegra30 supported now)

On 16-10-19, 21:19, Dmitry Osipenko wrote:
> 16.10.2019 17:58, Peter Geis пишет:
> > On Wed, Oct 16, 2019 at 9:29 AM Dmitry Osipenko <digetx@...il.com> wrote:
> >>
> >> 16.10.2019 08:18, Viresh Kumar пишет:
> >>> On 16-10-19, 00:16, Dmitry Osipenko wrote:
> >>>> Re-parenting to intermediate clock is supported now by the clock driver
> >>>> and thus there is no need in a customized CPUFreq driver, all that code
> >>>> is common for both Tegra20 and Tegra30. The available CPU freqs are now
> >>>> specified in device-tree in a form of OPPs, all users should update their
> >>>> device-trees.
> >>>>
> >>>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> >>>> ---
> >>>>  drivers/cpufreq/Kconfig.arm          |   4 +-
> >>>>  drivers/cpufreq/cpufreq-dt-platdev.c |   2 +
> >>>>  drivers/cpufreq/tegra20-cpufreq.c    | 236 ++++++---------------------
> >>>>  3 files changed, 55 insertions(+), 187 deletions(-)
> >>>>
> >>>> diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
> >>>> index a905796f7f85..2118c45d0acd 100644
> >>>> --- a/drivers/cpufreq/Kconfig.arm
> >>>> +++ b/drivers/cpufreq/Kconfig.arm
> >>>> @@ -301,8 +301,8 @@ config ARM_TANGO_CPUFREQ
> >>>>      default y
> >>>>
> >>>>  config ARM_TEGRA20_CPUFREQ
> >>>> -    tristate "Tegra20 CPUFreq support"
> >>>> -    depends on ARCH_TEGRA
> >>>> +    bool "Tegra20 CPUFreq support"
> >>>
> >>> Google is currently working on the GKI (generic kernel image) project where they
> >>> want to use a single kernel image with modules for all kind of android devices.
> >>> And for that they need all such drivers to be built as module. Since this is
> >>> already an module, I would ask you to keep it as is instead of moving it to bool
> >>> here. Else some google guy will switch it back as module later on.
> >>>
> >>> LGTM otherwise. Nice work. Thanks.
> >>>
> >>
> >> Okay, I'll keep the modularity in v2.
> >>
> >> Although, tegra20-cpufreq isn't a driver anymore because now it merely
> >> prepares OPP table for the cpufreq-dt driver, which is really a one-shot
> >> action that is enough to do during boot and thus modularity is a bit
> >> redundant here.
> > 
> > I doubt Google will care much, since Android has moved on to aarch64.
> > Do they even support arm32 any more?
> 
> Yes, I don't think there is a real need to care about Google. They won't
> use pure upstream and won't care about older hardware any ways.

Well, using (almost) pure upstream is the idea I believe. And the thing is they
want to use a single multi-platform image which should be as small as possible
in size. So it won't have any drivers or platform stuff (if possible) and
everything is module.

I am not sure about arm32/64 thing though. And it is okay if you don't want to
care about Google right now. That was just some side knowledge I had :)

-- 
viresh