linux-kernel - Re: [PATCH v27 05/11] soc: mediatek: refine code to use mtk_mmsys_update

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Date:   Thu, 3 Nov 2022 16:32:38 -0400
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     "Nancy.Lin" <nancy.lin@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>, wim@...ux-watchdog.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>, linux@...ck-us.net,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "jason-jh . lin" <jason-jh.lin@...iatek.com>,
        Yongqiang Niu <yongqiang.niu@...iatek.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org, llvm@...ts.linux.dev,
        singo.chang@...iatek.com,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v27 05/11] soc: mediatek: refine code to use
 mtk_mmsys_update_bits API

On Thu, Nov 03, 2022 at 11:25:06AM +0800, Nancy.Lin wrote:
[..]
> --- a/drivers/soc/mediatek/mtk-mmsys.c
> +++ b/drivers/soc/mediatek/mtk-mmsys.c
[..]
> +static void mtk_mmsys_update_bits(struct mtk_mmsys *mmsys, u32 offset, u32 mask, u32 val)
> +{
> +	u32 tmp;
> +
> +	tmp = readl_relaxed(mmsys->regs + offset);
> +	tmp = (tmp & ~mask) | val;

You should mask the value before writing to prevent bad values from overwriting
bits outside the mask.

	tmp = (tmp & ~mask) | (val & mask);

With that,

Reviewed-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

Thanks,
Nícolas