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Message-ID: <0a5fa878-b7c3-b5a3-8ffa-b3a2dcdc400d@wanadoo.fr>
Date: Sun, 2 Apr 2023 10:22:59 +0200
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: Stephen Boyd <sboyd@...nel.org>,
Michael Turquette <mturquette@...libre.com>
Cc: linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
linux-clk@...r.kernel.org
Subject: Re: [PATCH] clk: Reorder fields in 'struct clk_fractional_divider'
Le 29/03/2023 à 20:46, Stephen Boyd a écrit :
> Quoting Christophe JAILLET (2023-02-17 07:55:55)
>> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
>> index cf1adfeaf257..8cec844f5dde 100644
>> --- a/include/linux/clk-provider.h
>> +++ b/include/linux/clk-provider.h
>> @@ -1134,13 +1134,13 @@ struct clk_hw *clk_hw_register_fixed_factor_parent_hw(struct device *dev,
>> struct clk_fractional_divider {
>> struct clk_hw hw;
>> void __iomem *reg;
>> + u8 flags;
>> u8 mshift;
>> u8 mwidth;
>> u32 mmask;
>
> This member ...
>
>> u8 nshift;
>> u8 nwidth;
>> u32 nmask;
>
> and this member can be calculated. Doing that would save more bytes when
> combined with this patch. Can you make this into a patch series?
Hi,
with your proposed change, there is no more need to move flags. All u8
are grouped and the struct is optimal.
I'll send a v2, but not sure it really worth it.
When dynamically allocated, even when the struct is 56 bytes, 64 are
still allocated.
And there are only 2 users of struct clk_fractional_divider embedded in
another struct that will be shrinked with your change.
On the other side, having theses masks pre-computed could save a few
cycles, at nearly no memory usage impact.
I'll let you decide if v1 or v2 is the preferred way to go.
CJ
>
>> - u8 flags;
>> void (*approximation)(struct clk_hw *hw,
>> unsigned long rate, unsigned long *parent_rate,
>> unsigned long *m, unsigned long *n);
>
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