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Subject[PATCH v4 0/4] mfd: tps6586x: register restart handler
Date
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.

v3: https://lore.kernel.org/r/20230327-tegra-pmic-reboot-v3-0-3c0ee3567e14@skidata.com
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/

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 (4):
kernel/reboot: emergency_restart: set correct system_state
i2c: core: run atomic i2c xfer when !preemptible
mfd: tps6586x: use devm-based power off handler
mfd: tps6586x: register restart handler

drivers/i2c/i2c-core.h | 2 +-
drivers/mfd/tps6586x.c | 45 +++++++++++++++++++++++++++++++++++++--------
kernel/reboot.c | 1 +
3 files changed, 39 insertions(+), 9 deletions(-)
---
base-commit: 197b6b60ae7bc51dd0814953c562833143b292aa
change-id: 20230327-tegra-pmic-reboot-4175ff814a4b

Best regards,
--
Benjamin Bara <benjamin.bara@skidata.com>

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