linux-kernel - Re: [PATCH] clk: imx: imx8qxp-lpcg: use devm_platform_ioremap

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Date:   Wed, 4 Dec 2019 14:24:19 +0000
From:   Leonard Crestez <leonard.crestez@....com>
To:     Peng Fan <peng.fan@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Aisheng Dong <aisheng.dong@....com>
CC:     "sboyd@...nel.org" <sboyd@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        Abel Vesa <abel.vesa@....com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Alice Guo <alice.guo@....com>
Subject: Re: [PATCH] clk: imx: imx8qxp-lpcg: use
 devm_platform_ioremap_resource

On 2019-12-04 12:14 PM, Peng Fan wrote:
> From: Peng Fan <peng.fan@....com>
> 
> devm_platform_ioremap_resource() wraps platform_get_resource() and
> devm_ioremap_resource(), we could use this API to simplify the code.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>

This patch has been posted before and it breaks uart on imx8qxp-mek and 
possibly other things.

The old and new paths are not equivalent: devm_platform_ioremap_resource 
calls devm_ioremap_resource differs from devm_ioremap by also calling 
devm_request_mem_region.

This prevents other mappings in the area; this is not an issue for most 
drivers but imx8qxp-lpcg maps whole subsystems. For example:

                 adma_lpcg: clock-controller@...00000 {
                         compatible = "fsl,imx8qxp-lpcg-adma";
                         reg = <0x59000000 0x2000000>;
                         #clock-cells = <1>;
                 };

                 adma_lpuart0: serial@...60000 {
                         reg = <0x5a060000 0x1000>;
			...
		};

Previously: https://patchwork.kernel.org/patch/10908807/

> ---
>   drivers/clk/imx/clk-imx8qxp-lpcg.c | 8 ++------
>   1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> index c0aff7ca6374..3f2c2b068c73 100644
> --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> @@ -164,7 +164,6 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
>   	struct clk_hw_onecell_data *clk_data;
>   	const struct imx8qxp_ss_lpcg *ss_lpcg;
>   	const struct imx8qxp_lpcg_data *lpcg;
> -	struct resource *res;
>   	struct clk_hw **clks;
>   	void __iomem *base;
>   	int i;
> @@ -173,12 +172,9 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
>   	if (!ss_lpcg)
>   		return -ENODEV;
>   
> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	if (!res)
> -		return -EINVAL;
> -	base = devm_ioremap(dev, res->start, resource_size(res));
> +	base = devm_platform_ioremap_resource(pdev, 0);
>   	if (!base)
> -		return -ENOMEM;
> +		return PTR_ERR(base);
>   
>   	clk_data = devm_kzalloc(&pdev->dev, struct_size(clk_data, hws,
>   				ss_lpcg->num_max), GFP_KERNEL);
>