linux-kernel - Re: [PATCH] pinctrl: samsung: use 'int' for register masks in Exynos

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Date:   Fri, 9 Apr 2021 13:53:32 +0200
From:   Sylwester Nawrocki <s.nawrocki@...sung.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Tomasz Figa <tomasz.figa@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH] pinctrl: samsung: use 'int' for register masks in
 Exynos

On 08.04.2021 21:50, Krzysztof Kozlowski wrote:
> The Special Function Registers on all Exynos SoC, including ARM64, are
> 32-bit wide, so entire driver uses matching functions like readl() or
> writel().  On 64-bit ARM using unsigned long for register masks:
> 1. makes little sense as immediately after bitwise operation it will be
>    cast to 32-bit value when calling writel(),
> 2. is actually error-prone because it might promote other operands to
>    64-bit.
> 
> Addresses-Coverity: Unintentional integer overflow
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>

Reviewed-by: Sylwester Nawrocki <s.nawrocki@...sung.com>

> ---
> 
> Not tested on ARM64.

I have tested it on exynos5433/tm2e and didn't notice any issues
as we could expect. 
The patch looks good to me, however I would personally use u32
rather than "unsigned int", like in other places for the register
value variables.

--
Regards, 
Sylwester