From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: Jerome Brunet <jbrunet@baylibre.com>
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
Neil Armstrong <narmstrong@baylibre.com>,
khilman@baylibre.com, linux-kernel@vger.kernel.org,
robh+dt@kernel.org, linux-amlogic@lists.infradead.org,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/5] provide the XTAL clock via OF on Meson8/8b/8m2
Date: Mon, 23 Sep 2019 22:56:28 +0200 [thread overview]
Message-ID: <CAFBinCA0NaCJEDfNEg+LRfW3wxfNFGbXmGS+z7D5792TsupVAA@mail.gmail.com> (raw)
In-Reply-To: <1jzhivs6n6.fsf@starbuckisacylon.baylibre.com>
Hi Jerome,
On Mon, Sep 23, 2019 at 11:29 AM Jerome Brunet <jbrunet@baylibre.com> wrote:
>
> On Sat 21 Sep 2019 at 17:12, Martin Blumenstingl <martin.blumenstingl@googlemail.com> wrote:
>
> > So far the HHI clock controller has been providing the XTAL clock on
> > Amlogic Meson8/Meson8b/Meson8m2 SoCs.
> > This is not correct because the XTAL is actually a crystal on the
> > boards and the SoC has a dedicated input for it.
> >
> > This updates the dt-bindings of the HHI clock controller and defines
> > a fixed-clock in meson.dtsi (along with switching everything over to
> > use this clock).
> > The clock driver needs three updates to use this:
> > - patch #2 uses clk_hw_set_parent in the CPU clock notifier. This drops
> > the explicit reference to CLKID_XTAL while at the same time making
> > the code much easier (thanks to Neil for providing this new method
> > as part of the G12A CPU clock bringup!)
> > - patch #3 ensures that the clock driver doesn't rely on it's internal
> > XTAL clock while not losing support for older .dtbs that don't have
> > the XTAL clock input yet
> > - with patch #4 the clock controller's own XTAL clock is not registered
> > anymore when a clock input is provided via OF
> >
> > This series is a functional no-op. It's main goal is to better represent
> > how the actual hardware looks like.
>
> I'm a bit unsure about this series.
>
> On one hand, I totally agree with you ... having the xtal in DT is the
> right way to do it ... when done from the start
yep
> On the other hand, things have been this way for years, they are working
> and going for xtal in DT does not solve any pending issue. Doing this
> means adding complexity in the driver to support both methods. It is
> also quite a significant change in DT :/
my two main motivations were:
- keeping the 32-bit SoCs as similar as possible to the 64-bit ones in
terms of "how are the [clock] drivers implemented"
- with the DDR clock controller the .dts looked weird: &ddr_clkc took
CLKID_XTAL from &clkc as input and &clkc took DDR_CLKID_DDR_PLL as
input from &ddr_clkc
RE complexity in the driver to support both:
I still have a cleanup of the meson8b.c init code on my TODO-list
because we're still supporting .dtbs without parent syscon
my plan is to drop that code-path along with the newly added fallback
for "skip CLKID_XTAL" (assuming this is accepted) together for v5.6 or
v5.7
Martin
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next prev parent reply other threads:[~2019-09-23 20:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-21 15:12 [PATCH 0/5] provide the XTAL clock via OF on Meson8/8b/8m2 Martin Blumenstingl
2019-09-21 15:12 ` [PATCH 1/5] dt-bindings: clock: meson8b: add the clock inputs Martin Blumenstingl
2019-10-02 14:19 ` Rob Herring
2019-09-21 15:12 ` [PATCH 2/5] clk: meson: meson8b: use clk_hw_set_parent in the CPU clock notifier Martin Blumenstingl
2019-09-21 15:12 ` [PATCH 3/5] clk: meson: meson8b: change references to the XTAL clock to use the name Martin Blumenstingl
2019-09-21 15:12 ` [PATCH 4/5] clk: meson: meson8b: don't register the XTAL clock when provided via OF Martin Blumenstingl
2019-09-23 9:31 ` Jerome Brunet
2019-09-23 20:57 ` Martin Blumenstingl
2019-09-21 15:12 ` [PATCH 5/5] ARM: dts: meson: provide the XTAL clock using a fixed-clock Martin Blumenstingl
2019-09-23 9:29 ` [PATCH 0/5] provide the XTAL clock via OF on Meson8/8b/8m2 Jerome Brunet
2019-09-23 20:56 ` Martin Blumenstingl [this message]
2019-09-25 22:47 ` Kevin Hilman
2019-09-26 18:34 ` Martin Blumenstingl
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