Re: [PATCH] HID: intel_ish-hid: HBM: Use connected standby state bit during suspend/resume

Hi Srinivas

Thanks for the review.

On Tue, Mar 09, 2021 at 08:08:36AM -0800, Srinivas Pandruvada wrote:

On Tue, 2021-03-09 at 11:47 +0800, Ye, Xiang wrote:

quoted

Hi Srinivas, Jiri

On Mon, Mar 08, 2021 at 08:00:41AM -0800, Srinivas Pandruvada wrote:

quoted

On Mon, 2021-03-08 at 11:26 +0100, Jiri Kosina wrote:

quoted

On Wed, 3 Mar 2021, Ye Xiang wrote:

quoted

ISH firmware uses connected standby state bit
(CONNECTED_STANDBY_STATE_BIT bit 1)
to notify current power state to sensors instead of suspend
state
bit (bit 0).
So send both SUSPEND_STATE_BIT and CONNECTED_STANDBY_STATE_BIT
to
firmware
to be compatible with the previous version.

Could you please make the changelog more verbose -- namely what 
user-visible issue this is fixing?

Xiang,

I think this change is for related to Elkhart Lake for support of
connected standby (keep listening for sensor events during Linux
suspend for some sensors). In this way some sensor can wake up the
system.

This change is for all ISH platform. Currently, ISH firmware use
both SUSPEND_STATE_BIT and CONNECTED_STANDBY_STATE_BIT to identify
system state. It is related to system wake up by ISH and it enable
each
sensor in ISH to be notified the current system state, when system
state
change.

What will sensors do with this additional information?
I think the individual sensors in ISH can decide whether to power OFF
or ON based on this information to save power during system suspend to
idle.

Currently, In ISH firmware, we are using CONNECTED_STANDBY_STATE_BIT
(To be compatible with Windows os which are using CONNECTED_STANDBY_STATE_BIT) to
notify sensor system power state. Then some sensor(such as hinge sensor)
can power On/Off itself according to current system power state.

Thanks
Ye Xiang