Re: [PATCH 3/6] dt-bindings: HID: i2c-hid: elan: add 'no-reset-on-power-off' property

Johan Hovold
2024-05-03T09:25:04Z

On Fri, May 03, 2024 at 11:11:16AM +0200, Krzysztof Kozlowski wrote:
> On 02/05/2024 11:56, Johan Hovold wrote:
> > On Thu, Apr 25, 2024 at 11:39:24AM +0200, Krzysztof Kozlowski wrote:

> >> It seems it is common problem. LEDs have property
> >> "retain-state-shutdown", to indicate that during system shutdown we
> >> should not touch them (like power off). Would some variant be applicable
> >> here? First, do we talk here about power off like system shutdown or
> >> runtime PM, thus suspend?
> >
> > A name like 'retain-state-shutdown' would also be too specific as what
> > I'm describing here is that the reset line should be (or can be) left
> > deasserted whenever the OS wants to power off the device.
>
> I don't think it is more specific than yours. It is actually more
> generic. First, shutdown=poweroff, so that part is the same.

My point is that 'shutdown' is a specific OS concept (i.e. turning the
whole system off), while powering off a *device* can be done for a
number of reasons including closing a character device, suspend and
system-wide shutdown.

The policy decision of when to power off a device is left up to kernel
(e.g. if a device needs to be kept on as it is currently configured as a
wakeup device).

Johan