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 <peng.fan@nxp.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
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;