Re: [PATCH v2 1/1] firmware: arm_scmi: Add SCMI System Power Control driver

From: Sudeep Holla
Date: Thu Nov 12 2020 - 09:57:55 EST


On Mon, Oct 26, 2020 at 08:55:31PM +0000, Cristian Marussi wrote:
> Add an SCMI System Power control driver to handle platform's requests
> carried by SYSTEM_POWER_STATE_NOTIFIER notifications: such platform
> requested system power state transitions are handled accordingly,
> gracefully or forcefully, depending on the notifications' message flags.
>
> Graceful requests are by default relayed to userspace using the same
> Kernel API used to handle ACPI Shutdown bus events: alternatively, instead,
> a few available module parameters can be used to tunnel instead such
> requests to userspace via signals addressed to CAD pid.
>
> When handling graceful requests, grant userspace processes a maximum
> (configurable) time to perform their duties and then revert to a forceful
> transition, so avoiding completely timing out platform's maximum grace time
> and hitting possible abrupt power-cuts.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
> drivers/firmware/Kconfig | 12 +
> drivers/firmware/arm_scmi/Makefile | 1 +
> .../firmware/arm_scmi/scmi_power_control.c | 387 ++++++++++++++++++
> 3 files changed, 400 insertions(+)
> create mode 100644 drivers/firmware/arm_scmi/scmi_power_control.c
>

[nit] Since you have just one patch, it is generally preferred to place
all the extra non commit messages here after diff stat to have a single
thread of discussion.

Anyways, probably ccing Arnd/Greg/or anyone who has made some feature
changes in this area(e.g. kernel/reboot.c) might help to get some useful
feedback here.

--
Regards,
Sudeep