On 15/02/20, Anatolij Gustschin wrote:
> 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 <ag...@denx.de>
> Reported-by: Oliver Graute <oliver.gra...@gmail.com>
> Reported-by: Fabio Estevam <feste...@gmail.com>
>
> ---
> drivers/power/domain/power-domain-uclass.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/power/domain/power-domain-uclass.c
> b/drivers/power/domain/power-domain-uclass.c
> index d9c623b56e..d8fe4d4877 100644
> --- a/drivers/power/domain/power-domain-uclass.c
> +++ b/drivers/power/domain/power-domain-uclass.c
> @@ -127,6 +127,18 @@ 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
> --
> 2.17.1
thx, just tested this and now I can drop my revert mentioned here:
https://lists.denx.de/pipermail/u-boot/2020-February/398910.html
Best regards,
Oliver
