linux-kernel - Re: [PATCH v6 3/6] clk: spacemit: Add clock support for SpacemiT K1 SoC

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Message-ID: <dm4lwnplwcxj3t3qx3a3bdxtziowjfoqdy4vrd3ahmzkhejrov@fa5rujatatew>
Date: Thu, 10 Apr 2025 08:54:51 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Yixun Lan <dlan@...too.org>, Alex Elder <elder@...cstar.com>
Cc: Haylen Chu <heylenay@....org>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Haylen Chu <heylenay@...look.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Alexandre Ghiti <alex@...ti.fr>, linux-riscv@...ts.infradead.org, linux-clk@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, spacemit@...ts.linux.dev, 
	Inochi Amaoto <inochiama@...look.com>, Chen Wang <unicornxdotw@...mail.com>, 
	Jisheng Zhang <jszhang@...nel.org>, Meng Zhang <zhangmeng.kevin@...ux.spacemit.com>, 
	Inochi Amaoto <inochiama@...il.com>
Subject: Re: [PATCH v6 3/6] clk: spacemit: Add clock support for SpacemiT K1
 SoC

On Thu, Apr 10, 2025 at 12:37:56AM +0000, Yixun Lan wrote:
> On 14:37 Tue 08 Apr     , Alex Elder wrote:
> > On 4/1/25 12:24 PM, Haylen Chu wrote:
> > > The clock tree of K1 SoC contains three main types of clock hardware
> > > (PLL/DDN/MIX) and has control registers split into several multifunction
> > > devices: APBS (PLLs), MPMU, APBC and APMU.
> > > 
> > > All register operations are done through regmap to ensure atomiciy
> > > between concurrent operations of clock driver and reset,
> > > power-domain driver that will be introduced in the future.
> > > 
> > > Signed-off-by: Haylen Chu <heylenay@....org>
> > 
> > I have a few more comments here but I think this is getting very
> > close to ready.  You addressed pretty much everything I mentioned.
> > 
> > > ---
> > >   drivers/clk/Kconfig               |    1 +
> > >   drivers/clk/Makefile              |    1 +
> > >   drivers/clk/spacemit/Kconfig      |   18 +
> > >   drivers/clk/spacemit/Makefile     |    5 +
> > >   drivers/clk/spacemit/apbc_clks    |  100 +++
> > >   drivers/clk/spacemit/ccu-k1.c     | 1316 +++++++++++++++++++++++++++++
> > >   drivers/clk/spacemit/ccu_common.h |   48 ++
> > >   drivers/clk/spacemit/ccu_ddn.c    |   83 ++
> > >   drivers/clk/spacemit/ccu_ddn.h    |   47 ++
> > >   drivers/clk/spacemit/ccu_mix.c    |  268 ++++++
> > >   drivers/clk/spacemit/ccu_mix.h    |  218 +++++
> > >   drivers/clk/spacemit/ccu_pll.c    |  157 ++++
> > >   drivers/clk/spacemit/ccu_pll.h    |   86 ++
> > >   13 files changed, 2348 insertions(+)
> > >   create mode 100644 drivers/clk/spacemit/Kconfig
> > >   create mode 100644 drivers/clk/spacemit/Makefile
> > >   create mode 100644 drivers/clk/spacemit/apbc_clks
> > >   create mode 100644 drivers/clk/spacemit/ccu-k1.c
> > >   create mode 100644 drivers/clk/spacemit/ccu_common.h
> > >   create mode 100644 drivers/clk/spacemit/ccu_ddn.c
> > >   create mode 100644 drivers/clk/spacemit/ccu_ddn.h
> > >   create mode 100644 drivers/clk/spacemit/ccu_mix.c
> > >   create mode 100644 drivers/clk/spacemit/ccu_mix.h
> > >   create mode 100644 drivers/clk/spacemit/ccu_pll.c
> > >   create mode 100644 drivers/clk/spacemit/ccu_pll.h
> > > 
> > > diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> > > index 713573b6c86c..19c1ed280fd7 100644
> > > --- a/drivers/clk/Kconfig
> > > +++ b/drivers/clk/Kconfig
> > > @@ -517,6 +517,7 @@ source "drivers/clk/samsung/Kconfig"
> > >   source "drivers/clk/sifive/Kconfig"
> > >   source "drivers/clk/socfpga/Kconfig"
> > >   source "drivers/clk/sophgo/Kconfig"
> > > +source "drivers/clk/spacemit/Kconfig"
> > >   source "drivers/clk/sprd/Kconfig"
> > >   source "drivers/clk/starfive/Kconfig"
> > >   source "drivers/clk/sunxi/Kconfig"
> > > diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> > > index bf4bd45adc3a..42867cd37c33 100644
> > > --- a/drivers/clk/Makefile
> > > +++ b/drivers/clk/Makefile
> > > @@ -145,6 +145,7 @@ obj-$(CONFIG_COMMON_CLK_SAMSUNG)	+= samsung/
> > >   obj-$(CONFIG_CLK_SIFIVE)		+= sifive/
> > >   obj-y					+= socfpga/
> > >   obj-y					+= sophgo/
> > > +obj-y					+= spacemit/
> > >   obj-$(CONFIG_PLAT_SPEAR)		+= spear/
> > >   obj-y					+= sprd/
> > >   obj-$(CONFIG_ARCH_STI)			+= st/
> > > diff --git a/drivers/clk/spacemit/Kconfig b/drivers/clk/spacemit/Kconfig
> > > new file mode 100644
> > > index 000000000000..4c4df845b3cb
> > > --- /dev/null
> > > +++ b/drivers/clk/spacemit/Kconfig
> > > @@ -0,0 +1,18 @@
> > > +# SPDX-License-Identifier: GPL-2.0-only
> > > +
> > > +config SPACEMIT_CCU
> > > +	tristate "Clock support for SpacemiT SoCs"
> > 
> > I don't know the answer to this, but...  Should this be a Boolean
> > rather than tristate?  Can a SpacemiT K1 SoC function without the
> > clock driver built in to the kernel?
> > 
> I agree to make it a Boolean, we've already made pinctrl driver Boolean
> and pinctrl depend on clk, besides, the SoC is unlikely functional
> without clock built in as it's such critical..
> 

I disagree. The kernel is only for spacemit only, and the pinctrl
should also be a module. It is the builder's right to decide whether
the driver is builtin or a module. In this view, you should always
allow the driver to be built as a module if possible.

Regards,
Inochi