linux-kernel - Re: [PATCH v2 2/4] clk: spacemit: introduce pre-div for ddn clock

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Message-ID: <aKKKNynq-w89YeAx@ketchup>
Date: Mon, 18 Aug 2025 02:04:39 +0000
From: Haylen Chu <heylenay@....org>
To: Troy Mitchell <troy.mitchell@...ux.spacemit.com>,
	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>, Yixun Lan <dlan@...too.org>,
	Alex Elder <elder@...cstar.com>,
	Inochi Amaoto <inochiama@...look.com>
Cc: linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
	linux-riscv@...ts.infradead.org, spacemit@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Jinmei Wei <weijinmei@...ux.spacemit.com>
Subject: Re: [PATCH v2 2/4] clk: spacemit: introduce pre-div for ddn clock

On Mon, Aug 11, 2025 at 10:04:28PM +0800, Troy Mitchell wrote:
> The original DDN operations applied an implicit divide-by-2, which should
> not be a default behavior.
> 
> This patch removes that assumption, letting each clock define its
> actual behavior explicitly.
> 
> Signed-off-by: Troy Mitchell <troy.mitchell@...ux.spacemit.com>
> ---
>  drivers/clk/spacemit/ccu_ddn.c | 12 ++++++------
>  drivers/clk/spacemit/ccu_ddn.h |  6 ++++--
>  2 files changed, 10 insertions(+), 8 deletions(-)

The code change looks good to me, but

> diff --git a/drivers/clk/spacemit/ccu_ddn.h b/drivers/clk/spacemit/ccu_ddn.h
> index a52fabe77d62eba16426867a9c13481e72f025c0..4838414a8e8dc04af49d3b8d39280efedbd75616 100644
> --- a/drivers/clk/spacemit/ccu_ddn.h
> +++ b/drivers/clk/spacemit/ccu_ddn.h
> @@ -18,13 +18,14 @@ struct ccu_ddn {
>  	unsigned int num_shift;
>  	unsigned int den_mask;
>  	unsigned int den_shift;
> +	unsigned int pre_div;
>  };
>  
>  #define CCU_DDN_INIT(_name, _parent, _flags) \
>  	CLK_HW_INIT_HW(#_name, &_parent.common.hw, &spacemit_ccu_ddn_ops, _flags)
>  
>  #define CCU_DDN_DEFINE(_name, _parent, _reg_ctrl, _num_shift, _num_width,	\
> -		       _den_shift, _den_width, _flags)				\
> +		       _den_shift, _den_width, _pre_div, _flags)		\

You changed the definition of CCU_DDN_DEFINE without adjusting consumers
of this macro. If I'm correct, this creates a build failure.

>  static struct ccu_ddn _name = {							\
>  	.common = {								\
>  		.reg_ctrl	= _reg_ctrl,					\
> @@ -33,7 +34,8 @@ static struct ccu_ddn _name = {							\
>  	.num_mask	= GENMASK(_num_shift + _num_width - 1, _num_shift),	\
>  	.num_shift	= _num_shift,						\
>  	.den_mask	= GENMASK(_den_shift + _den_width - 1, _den_shift),	\
> -	.den_shift	= _den_shift,					\
> +	.den_shift	= _den_shift,						\
> +	.pre_div	= _pre_div,						\
>  }
>  
>  static inline struct ccu_ddn *hw_to_ccu_ddn(struct clk_hw *hw)
> 
> -- 
> 2.50.1
> 

Best regards,
Haylen Chu