Hello Guodong,

On Fri, May 26, 2017 at 8:35 AM, Guodong Xu [off-list ref] wrote:

From: Wang Xiaoyin <redacted>

[snip]

+config REGULATOR_HI6421V530
+       tristate "HiSilicon Hi6421v530 PMIC voltage regulator support"

The Kconfig symbol is tristate so the driver can be built as a module...

+
+static struct platform_driver hi6421v530_regulator_driver = {
+       .driver = {
+               .name   = "hi6421v530-regulator",
+       },
+       .probe  = hi6421v530_regulator_probe,
+};
+module_platform_driver(hi6421v530_regulator_driver);

... but the driver doesn't have a platform device ID table nor export
it as a module alias using MODULE_DEVICE_TABLE().

That means that if built as a module, it won't be autoloaded when the
"hi6421v530-regulator" device is registered by the MFD driver.

+
+MODULE_AUTHOR("Wang Xiaoyin [off-list ref]");
+MODULE_DESCRIPTION("Hi6421v530 regulator driver");
+MODULE_LICENSE("GPL v2");

Alternative you can add a MODULE_ALIAS().

Best regards,
Javier