linux-kernel - Re: [PATCH 1/3] clk: mediatek: clk-mtk: Grab iomem pointer for divider clocks

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Date:   Fri, 16 Jun 2023 10:43:14 +0200
From:   Markus Schneider-Pargmann <msp@...libre.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     sboyd@...nel.org, mturquette@...libre.com, matthias.bgg@...il.com,
        wenst@...omium.org, u.kleine-koenig@...gutronix.de,
        miles.chen@...iatek.com, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH 1/3] clk: mediatek: clk-mtk: Grab iomem pointer for
 divider clocks

On Thu, Jun 15, 2023 at 02:20:49PM +0200, AngeloGioacchino Del Regno wrote:
> In the rare case in which one of the clock drivers has divider clocks
> but not composite clocks, mtk_clk_simple_probe() would not io(re)map,
> hence passing a NULL pointer to mtk_clk_register_dividers().
> 
> To fix this issue, extend the `if` conditional to also check if any
> divider clocks are present. While at it, also make sure the iomem
> pointer is NULL if no composite/divider clocks are declared, as we
> are checking for that when iounmapping it in the error path.
> 
> This hasn't been seen on any MediaTek clock driver as the current ones
> always declare composite clocks along with divider clocks, but this is
> still an important fix for a future potential KP.
> 
> Fixes: 1fe074b1f112 ("clk: mediatek: Add divider clocks to mtk_clk_simple_{probe,remove}()")
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Reviewed-by: Markus Schneider-Pargmann <msp@...libre.com>

> ---
>  drivers/clk/mediatek/clk-mtk.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/mediatek/clk-mtk.c b/drivers/clk/mediatek/clk-mtk.c
> index cf3514c8e97e..b00ef4213335 100644
> --- a/drivers/clk/mediatek/clk-mtk.c
> +++ b/drivers/clk/mediatek/clk-mtk.c
> @@ -469,7 +469,7 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
>  	const struct platform_device_id *id;
>  	const struct mtk_clk_desc *mcd;
>  	struct clk_hw_onecell_data *clk_data;
> -	void __iomem *base;
> +	void __iomem *base = NULL;
>  	int num_clks, r;
>  
>  	mcd = device_get_match_data(&pdev->dev);
> @@ -483,8 +483,8 @@ static int __mtk_clk_simple_probe(struct platform_device *pdev,
>  			return -EINVAL;
>  	}
>  
> -	/* Composite clocks needs us to pass iomem pointer */
> -	if (mcd->composite_clks) {
> +	/* Composite and divider clocks needs us to pass iomem pointer */
> +	if (mcd->composite_clks || mcd->divider_clks) {
>  		if (!mcd->shared_io)
>  			base = devm_platform_ioremap_resource(pdev, 0);
>  		else
> -- 
> 2.40.1
>