linux-kernel - Re: [RFC PATCH 0/7] clk: sunxi-ng: Add a RTC CCU driver

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Message-ID: <20210903145013.hn6dv7lfyvfys374@gilmour>
Date:   Fri, 3 Sep 2021 16:50:13 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/7] clk: sunxi-ng: Add a RTC CCU driver

Hi,

On Wed, Sep 01, 2021 at 12:39:44AM -0500, Samuel Holland wrote:
> This patch series adds a CCU driver for the RTC in the H616 and R329.
> The extra patches at the end of this series show how it would be
> explanded to additional hardware variants.
> 
> The driver is intended to support the existing binding used for the H6,
> but also an updated binding which includes all RTC input clocks. I do
> not know how to best represent that binding -- that is a major reason
> why this series is an RFC.
> 
> A future patch series could add functionality to the driver to manage
> IOSC calibration at boot and during suspend/resume.
> 
> It may be possible to support all of these hardware variants in the
> existing RTC clock driver and avoid some duplicate code, but I'm
> concerned about the complexity there, without any of the CCU
> abstraction.
> 
> This series is currently based on top of the other series I just sent
> (clk: sunxi-ng: Lifetime fixes and module support), but I can rebase it
> elsewhere.

I'm generally ok with this, it makes sense to move it to sunxi-ng,
especially with that other series of yours.

My main concern about this is the split driver approach. We used to have
that before in the RTC too, but it was mostly due to the early clock
requirements. With your previous work, that requirement is not there
anymore and we can just register it as a device just like the other
clock providers.

And since we can register all those clocks at device probe time, we
don't really need to split the driver in two (and especially in two
different places). The only obstacle to this after your previous series
is that we don't have of_sunxi_ccu_probe / devm_sunxi_ccu_probe
functions public, but that can easily be fixed by moving their
definition to include/linux/clk/sunxi-ng.h

Maxime

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