From 249fce6f3ab0dbd98caa9bc8ea4b50fa709e786a Mon Sep 17 00:00:00 2001 From: Leonard Crestez Date: Mon, 9 Dec 2019 22:56:28 +0200 Subject: [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource On imx8 the LPCG nodes map entire subsystems and overlap peripherals, this means that using devm_platform_ioremap_resource will cause many devices to fail to probe including serial ports. Well-meaning but boot-breaking patches were posted multiple times so add a comment explaining this issue. Suggested-by: Peng Fan Signed-off-by: Leonard Crestez Reviewed-by: Peng Fan Signed-off-by: Shawn Guo --- drivers/clk/imx/clk-imx8qxp-lpcg.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-imx8qxp-lpcg.c index c0aff7ca6374..04c8ee35e14c 100644 --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c @@ -173,6 +173,17 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev) if (!ss_lpcg) return -ENODEV; + /* + * Please don't replace this with devm_platform_ioremap_resource. + * + * devm_platform_ioremap_resource calls devm_ioremap_resource which + * differs from devm_ioremap by also calling devm_request_mem_region + * and preventing other mappings in the same area. + * + * On imx8 the LPCG nodes map entire subsystems and overlap + * peripherals, this means that using devm_platform_ioremap_resource + * will cause many devices to fail to probe including serial ports. + */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!res) return -EINVAL;