Hi, On 17/02/2020 10:07, Oliver Graute wrote: > 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
The revert is still needed... it breaks multiple amlogic boards and the fix is not as simple as this one. Neil > > Best regards, > > Oliver >