linux-kernel - Re: [PATCH] gpio: dwapb: Fold dwapb_context into dwapb_gpio

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Message-ID: <CACRpkda=vNOq+QUZT71VwkTy6qz6yhu7zA3hYWTfc2GkptXFMw@mail.gmail.com>
Date: Wed, 19 Nov 2025 18:28:33 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Jisheng Zhang <jszhang@...nel.org>
Cc: Hoan Tran <hoan@...amperecomputing.com>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Andy Shevchenko <andy@...nel.org>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-riscv@...ts.infradead.org, Michael Büsch <mb@...s.ch>
Subject: Re: [PATCH] gpio: dwapb: Fold dwapb_context into dwapb_gpio_port

On Wed, Nov 19, 2025 at 4:18 PM Jisheng Zhang <jszhang@...nel.org> wrote:

> Fold dwapb_context into struct dwapb_gpio_port to further simplify
> the code. Sure this brings a tiny 36 bytes data overhead for
> !PM_SLEEP. After grepping the arm/arm64/riscv dts dir, the max dwapb
> gpio port number is 6(the berlin2q soc family), so this means we will
> waste 216 bytes memory in total which is trivial compared to the
> system memory.
>
> From another side, as Michael mentioned:
> "The driver currently allocates the struct with kzalloc and stores a
> pointer to it in case of PM=y.
> So this probably has an overhead in the same order of magnitude
> (pointer + malloc overhead/alignment/fragmentation) in case of PM=y
> now."
>
> So let's Fold dwapb_context into struct dwapb_gpio_port.
>
> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> CC: Michael Büsch <mb@...s.ch>

Neat.
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij