linux-kernel - Re: [PATCH] memory: mtk-smi: Use of_device_get_match

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Message-ID: <1d31eedd-fdab-bd6f-65b1-c0e8b79a8888@arm.com>
Date:   Wed, 26 Jul 2017 11:36:52 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     honghui.zhang@...iatek.com, joro@...tes.org,
        matthias.bgg@...il.com, robh@...nel.org
Cc:     srv_heupstream@...iatek.com, catalin.marinas@....com,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, youlin.pei@...iatek.com,
        erin.lo@...iatek.com
Subject: Re: [PATCH] memory: mtk-smi: Use of_device_get_match_data helper

On 26/07/17 10:59, honghui.zhang@...iatek.com wrote:
> From: Honghui Zhang <honghui.zhang@...iatek.com>
> 
> Replace custom code with generic helper to retrieve driver data.
> 
> Signed-off-by: Honghui Zhang <honghui.zhang@...iatek.com>
> ---
>  drivers/memory/mtk-smi.c | 18 ++++--------------
>  1 file changed, 4 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c
> index 4afbc41..fe8b81a 100644
> --- a/drivers/memory/mtk-smi.c
> +++ b/drivers/memory/mtk-smi.c
> @@ -240,20 +240,15 @@ static int mtk_smi_larb_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct device_node *smi_node;
>  	struct platform_device *smi_pdev;
> -	const struct of_device_id *of_id;
>  
>  	if (!dev->pm_domain)
>  		return -EPROBE_DEFER;
>  
> -	of_id = of_match_node(mtk_smi_larb_of_ids, pdev->dev.of_node);
> -	if (!of_id)
> -		return -EINVAL;
> -
>  	larb = devm_kzalloc(dev, sizeof(*larb), GFP_KERNEL);
>  	if (!larb)
>  		return -ENOMEM;
>  
> -	larb->larb_gen = of_id->data;
> +	larb->larb_gen = of_device_get_match_data(dev);
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	larb->base = devm_ioremap_resource(dev, res);
>  	if (IS_ERR(larb->base))
> @@ -319,8 +314,7 @@ static int mtk_smi_common_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct mtk_smi *common;
>  	struct resource *res;
> -	const struct of_device_id *of_id;
> -	enum mtk_smi_gen smi_gen;
> +	const enum mtk_smi_gen *smi_gen;
>  
>  	if (!dev->pm_domain)
>  		return -EPROBE_DEFER;
> @@ -338,18 +332,14 @@ static int mtk_smi_common_probe(struct platform_device *pdev)
>  	if (IS_ERR(common->clk_smi))
>  		return PTR_ERR(common->clk_smi);
>  
> -	of_id = of_match_node(mtk_smi_common_of_ids, pdev->dev.of_node);
> -	if (!of_id)
> -		return -EINVAL;
> -
>  	/*
>  	 * for mtk smi gen 1, we need to get the ao(always on) base to config
>  	 * m4u port, and we need to enable the aync clock for transform the smi
>  	 * clock into emi clock domain, but for mtk smi gen2, there's no smi ao
>  	 * base.
>  	 */
> -	smi_gen = (enum mtk_smi_gen)of_id->data;
> -	if (smi_gen == MTK_SMI_GEN1) {
> +	smi_gen = of_device_get_match_data(dev);

The data you're retrieving is the exact same thing as of_id->data was,
i.e. an enum mtk_smi_gen cast to void*, so dereferencing it is not a
good idea. The first patch was almost right; you just need to keep the
cast in the assignment to smi_gen.

Robin.

> +	if (*smi_gen == MTK_SMI_GEN1) {
>  		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  		common->smi_ao_base = devm_ioremap_resource(dev, res);
>  		if (IS_ERR(common->smi_ao_base))
>