linux-kernel - Re: [PATCH v2 1/2] phy: mediatek: hdmi: mt8195: fix uninitialized variable usage in pll

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Message-ID: <20230421221330.GA3657732@dev-arch.thelio-3990X>
Date:   Fri, 21 Apr 2023 15:13:30 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Guillaume Ranquet <granquet@...libre.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Vinod Koul <vkoul@...nel.org>,
        Kishon Vijay Abraham I <kishon@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel test robot <lkp@...el.com>, llvm@...ts.linux.dev
Subject: Re: [PATCH v2 1/2] phy: mediatek: hdmi: mt8195: fix uninitialized
 variable usage in pll_calc

On Fri, Apr 14, 2023 at 06:07:46PM +0200, Guillaume Ranquet wrote:
> The ret variable in mtk_hdmi_pll_calc() was used unitialized as reported
> by the kernel test robot.
> 
> Fix the issue by removing the variable altogether and testing out the
> return value of mtk_hdmi_pll_set_hw()
> 
> Fixes: 45810d486bb44 ("phy: mediatek: add support for phy-mtk-hdmi-mt8195")
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

Can somebody pick this up? It fixes a rather obvious warning, which is
breaking clang builds (as evidenced by three versions of the same fix).

> ---
>  drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c | 8 ++------
>  1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> index abfc077fb0a8..054b73cb31ee 100644
> --- a/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> +++ b/drivers/phy/mediatek/phy-mtk-hdmi-mt8195.c
> @@ -213,7 +213,7 @@ static int mtk_hdmi_pll_calc(struct mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
>  	u64 tmds_clk, pixel_clk, da_hdmitx21_ref_ck, ns_hdmipll_ck, pcw;
>  	u8 txpredivs[4] = { 2, 4, 6, 12 };
>  	u32 fbkdiv_low;
> -	int i, ret;
> +	int i;
>  
>  	pixel_clk = rate;
>  	tmds_clk = pixel_clk;
> @@ -292,13 +292,9 @@ static int mtk_hdmi_pll_calc(struct mtk_hdmi_phy *hdmi_phy, struct clk_hw *hw,
>  	if (!(digital_div <= 32 && digital_div >= 1))
>  		return -EINVAL;
>  
> -	mtk_hdmi_pll_set_hw(hw, PLL_PREDIV, fbkdiv_high, fbkdiv_low,
> +	return mtk_hdmi_pll_set_hw(hw, PLL_PREDIV, fbkdiv_high, fbkdiv_low,
>  			    PLL_FBKDIV_HS3, posdiv1, posdiv2, txprediv,
>  			    txposdiv, digital_div);
> -	if (ret)
> -		return -EINVAL;
> -
> -	return 0;
>  }
>  
>  static int mtk_hdmi_pll_drv_setting(struct clk_hw *hw)
> 
> -- 
> 2.40.0
>