| Message ID | 20200217084211.17967-1-agust@denx.de |
|---|---|
| State | Accepted |
| Commit | 3e4fcfa4bcd74fee409694d24ee580a2826bbe9a |
| Headers | show |
| Series | [v2] power-domain: fix hang in endless loop on i.MX8 | expand |
On Mon, Feb 17, 2020 at 09:42:11AM +0100, 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 at 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 Applied to u-boot/master, thanks!
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
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 at 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 at denx.de> Reported-by: Oliver Graute <oliver.graute at gmail.com> Reported-by: Fabio Estevam <festevam at gmail.com> Reviewed-by: Simon Glass <sjg at chromium.org> Reviewed-by: Lokesh Vutla <lokeshvutla at ti.com> --- Changes in v2: - drop braces - add RB tags drivers/power/domain/power-domain-uclass.c | 11 +++++++++++ 1 file changed, 11 insertions(+)