Re: [PATCH] clk: imx: imx8qxp-lpcg: use devm_platform_ioremap_resource

From: Leonard Crestez
Date: Wed Dec 04 2019 - 09:24:26 EST


On 2019-12-04 12:14 PM, Peng Fan wrote:
> From: Peng Fan <peng.fan@xxxxxxx>
>
> 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@xxxxxxx>

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@59000000 {
compatible = "fsl,imx8qxp-lpcg-adma";
reg = <0x59000000 0x2000000>;
#clock-cells = <1>;
};

adma_lpuart0: serial@5a060000 {
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);
>