Hi!

The Tegra20 requires an enabled VDE power domain during startup. As the VDE is currently not used, it is disabled during runtime. Since 8f0c714ad9be, there is a workaround for the "normal restart path" which enables the VDE before doing PMC's warm reboot. This workaround is not executed in the "emergency restart path", leading to a hang-up during start.

This series implements and registers a new pmic-based restart handler for boards with tps6586x. This cold reboot ensures that the VDE power domain is enabled during startup on tegra20-based boards.

Since bae1d3a05a8b, i2c transfers are non-atomic while preemption is disabled (which is e.g. done during panic()). This could lead to warnings ("Voluntary context switch within RCU") in i2c-based restart handlers during emergency restart. The state of preemption should be detected by i2c_in_atomic_xfer_mode() to use atomic i2c xfer when required. Beside the new system_state check, the check is the same as the one pre v5.2.

v4: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v4-0-b24af219fb47@skida... v3: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v3-0-3c0ee3567e14@skida... v2: https://lore.kernel.org/all/20230320220345.1463687-1-bbara93@gmail.com/ system_state: https://lore.kernel.org/all/20230320213230.1459532-1-bbara93@gmail.com/ v1: https://lore.kernel.org/all/20230316164703.1157813-1-bbara93@gmail.com/

v5: - introduce new 3 & 4, therefore 3 -> 5, 4 -> 6 - 3: provide dev to sys_off handler, if it is known - 4: return NOTIFY_DONE from sys_off_notify, to avoid skipping - 5: drop Reviewed-by from Dmitry, add poweroff timeout - 5,6: return notifier value instead of direct errno from handler - 5,6: use new dev field instead of passing dev as cb_data - 5,6: increase timeout values based on error observations - 6: skip unsupported reboot modes in restart handler

v4: - 1,2: add "Fixes" and adapt commit messages - 4: reduce delay after requesting the restart (as suggested by Dmitry)

v3: - bring system_state back in this series - do atomic i2c xfer if not preemptible (as suggested by Dmitry) - fix style issues mentioned by Dmitry - add cc stable as suggested by Dmitry - add explanation why this is needed for Jon

v2: - use devm-based restart handler - convert the existing power_off handler to a devm-based handler - handle system_state in extra series

--- Benjamin Bara (6): kernel/reboot: emergency_restart: set correct system_state i2c: core: run atomic i2c xfer when !preemptible kernel/reboot: add device to sys_off_handler kernel/reboot: sys_off_notify: always return NOTIFY_DONE mfd: tps6586x: use devm-based power off handler mfd: tps6586x: register restart handler

drivers/i2c/i2c-core.h | 2 +- drivers/mfd/tps6586x.c | 55 ++++++++++++++++++++++++++++++++++++++++++-------- include/linux/reboot.h | 3 +++ kernel/reboot.c | 11 +++++++++- 4 files changed, 61 insertions(+), 10 deletions(-) --- base-commit: 197b6b60ae7bc51dd0814953c562833143b292aa change-id: 20230327-tegra-pmic-reboot-4175ff814a4b

Best regards,