Currently when booting the kernel on i.MX8 U-Boot hangs in an endless loop when switching off dma, connectivity or lsio power domains during device removal. It hapens first when removing gpio0 (gpio@5d080000) device, here its power domain device 'lsio_gpio0' is obtained for switching off power. Since the obtained 'lsio_gpio0' device is removed afterwards, its power domain is also switched off and here the parent power domain device 'lsio_power_domain' is optained for switching off the power. Thereafter, when the obtained 'lsio_power_domain' is removed, device_remove() removes its first child 'lsio_gpio0'. During this child removal the 'lsio_power_domain' device is obtained again for switching and when removing it later, the same child removal is repeated, so we are stuck in an endless loop. Below is a snippet from dm tree on i.MX8QXP for better illustration of the DM devices relationship:

Class Index Probed Driver Name ----------------------------------------------------------- root 0 [ + ] root_driver root_driver ... simple_bus 0 [ + ] generic_simple_bus |-- imx8qx-pm power_doma 0 [ + ] imx8_power_domain | |-- lsio_power_domain power_doma 1 [ + ] imx8_power_domain | | |-- lsio_gpio0 power_doma 2 [ + ] imx8_power_domain | | |-- lsio_gpio1

Do not remove a power domain device if it is a parent of the currently controlled device.

Fixes: 52edfed65de9 ("dm: core: device: switch off power domain after device removal") Signed-off-by: Anatolij Gustschin agust@denx.de Reported-by: Oliver Graute oliver.graute@gmail.com Reported-by: Fabio Estevam festevam@gmail.com Reviewed-by: Simon Glass sjg@chromium.org Reviewed-by: Lokesh Vutla lokeshvutla@ti.com --- Changes in v2: - drop braces - add RB tags

drivers/power/domain/power-domain-uclass.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/drivers/power/domain/power-domain-uclass.c b/drivers/power/domain/power-domain-uclass.c index d9c623b56e..2b7a1cb8fe 100644 --- a/drivers/power/domain/power-domain-uclass.c +++ b/drivers/power/domain/power-domain-uclass.c @@ -127,6 +127,17 @@ static int dev_power_domain_ctrl(struct udevice *dev, bool on) ret = power_domain_off(&pd); }

+ /* + * For platforms with parent and child power-domain devices + * we may not run device_remove() on the power-domain parent + * because it will result in removing its children and switching + * off their power-domain parent. So we will get here again and + * again and will be stuck in an endless loop. + */ + if (!on && dev_get_parent(dev) == pd.dev && + device_get_uclass_id(dev) == UCLASS_POWER_DOMAIN) + return ret; + /* * power_domain_get() bound the device, thus * we must remove it again to prevent unbinding