From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: Jisheng Zhang <jszhang@kernel.org>
Cc: "Hoan Tran" <hoan@os.amperecomputing.com>,
"Linus Walleij" <linus.walleij@linaro.org>,
"Bartosz Golaszewski" <brgl@bgdev.pl>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
"Michael Büsch" <mb@bues.ch>
Subject: Re: [PATCH v2] gpio: dwapb: Fold dwapb_context into dwapb_gpio_port
Date: Mon, 24 Nov 2025 09:56:48 +0200 [thread overview]
Message-ID: <aSQPwEJhsUxuDAmH@smile.fi.intel.com> (raw)
In-Reply-To: <20251124003206.25618-1-jszhang@kernel.org>
On Mon, Nov 24, 2025 at 08:32:06AM +0800, Jisheng Zhang 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.
Fold --> fold
Given more thinking on this, I believe the approach with kmalloc() is
preferable, but what should be done is
- making context a global variable
- considering allocation for all ports at once
If this is done, the embedded approach will look less efficient.
So, please try that one instead.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2025-11-24 7:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-24 0:32 Jisheng Zhang
2025-11-24 7:56 ` Andy Shevchenko [this message]
2025-11-24 7:57 ` Andy Shevchenko
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