From: Kevin Hilman <khilman@baylibre.com>
To: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
Subject: Re: [PATCH] ARM: multi_v7_defconfig: switch CONFIG_PWM_MESON to built-in
Date: Thu, 29 Nov 2018 15:28:42 -0800 [thread overview]
Message-ID: <7hk1kv79at.fsf@baylibre.com> (raw)
In-Reply-To: <CAFBinCBViZgRrZO16FsRKSGNriSw2_D9+_6ri99_zf++_SuuKg@mail.gmail.com>
Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:
> Hi Kevin,
>
> On Thu, Nov 29, 2018 at 1:30 AM Kevin Hilman <khilman@baylibre.com> wrote:
>>
>> Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:
>>
>> > Some Meson8b boards (Odroid-C1, EC-100) use a PWM regulator which is the
>> > voltage supply of the CPU cores (this regulator is typically called
>> > "VCCK").
>> > Now that we are preparing support for CPU frequency scaling on Meson8,
>> > Meson8b and Meson8m2 we should build the pwm-meson driver into the
>> > kernel so we can configure the CPU voltage early in the boot process.
>>
>> Can you explain a little more why the configuration of CPU voltage
>> cannot wait a bit so this could be properly probed?
>
> I was under the impression that cpufreq-dt would still initialize even
> if the regulator is not ready yet. however (after reading the code
> again) this is clearly NOT the case.
Hmm, a quick look at cpufreq-dt suggests that it should -EPROBE_DEFER if
the regulator isn't ready yet. Why doesn't that work?
> there's still a benefit with this change: your Odroid-C1 in your
> KernelCI lab would also be able to change the CPU frequency (so in
> case something breaks we could spot it there).
> will you accept this patch after I updated the description to mention
> that it's for KernelCI test coverage?
Possibly, but I'd still rather see the dependencies worked out correctly
so that this can be module, and cpufreq-dt would defer until it's ready.
Kevin
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next prev parent reply other threads:[~2018-11-29 23:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-14 23:05 [PATCH] ARM: multi_v7_defconfig: switch CONFIG_PWM_MESON to built-in Martin Blumenstingl
2018-11-29 0:30 ` Kevin Hilman
2018-11-29 22:35 ` Martin Blumenstingl
2018-11-29 23:28 ` Kevin Hilman [this message]
2018-11-29 23:37 ` Martin Blumenstingl
2018-11-30 0:51 ` Kevin Hilman
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