linux-kernel - Re: [PATCH v4] drm/mediatek: Fix mtk_cec

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Date:   Tue, 4 Jan 2022 08:00:54 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Miles Chen <miles.chen@...iatek.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Junzhi Zhao <junzhi.zhao@...iatek.com>,
        Jie Qiu <jie.qiu@...iatek.com>,
        Zhiqiang Lin <zhiqiang.lin@...iatek.com>,
        CK Hu <ck.hu@...iatek.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] drm/mediatek: Fix mtk_cec_mask()

Hi, Miles:

Miles Chen <miles.chen@...iatek.com> 於 2022年1月3日 週一 下午1:47寫道：
>
> In current implementation, mtk_cec_mask() writes val into target register
> and ignores the mask. After talking to our hdmi experts, mtk_cec_mask()
> should read a register, clean only mask bits, and update (val | mask) bits
> to the register.

Reviewed-by: Chun-Kuang Hu <chunkuang.hu@...nel.org>

>
> Fixes: 8f83f26891e1 ("drm/mediatek: Add HDMI support")
>
> Cc: Zhiqiang Lin <zhiqiang.lin@...iatek.com>
> Cc: CK Hu <ck.hu@...iatek.com>
> Cc: Matthias Brugger <matthias.bgg@...il.com>
>
> Signed-off-by: Miles Chen <miles.chen@...iatek.com>
>
> ---
>
> Change since v1:
> add Fixes tag
>
> Change since v2:
> add explanation of mtk_cec_mask()
>
> Change since v3:
> change misleading subject and modify the commit message since this is a bug fix patch
>
> ---
>  drivers/gpu/drm/mediatek/mtk_cec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_cec.c b/drivers/gpu/drm/mediatek/mtk_cec.c
> index e9cef5c0c8f7..cdfa648910b2 100644
> --- a/drivers/gpu/drm/mediatek/mtk_cec.c
> +++ b/drivers/gpu/drm/mediatek/mtk_cec.c
> @@ -85,7 +85,7 @@ static void mtk_cec_mask(struct mtk_cec *cec, unsigned int offset,
>         u32 tmp = readl(cec->regs + offset) & ~mask;
>
>         tmp |= val & mask;
> -       writel(val, cec->regs + offset);
> +       writel(tmp, cec->regs + offset);
>  }
>
>  void mtk_cec_set_hpd_event(struct device *dev,
> --
> 2.18.0
>