Re: [PATCH v2] Input: document inhibiting

From: Pavel Machek <pavel@ucw.cz>
To: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Cc: linux-pm@vger.kernel.org, linux-acpi@vger.kernel.org,
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Subject: Re: [PATCH v2] Input: document inhibiting
Date: Tue, 23 Jun 2020 15:35:12 +0200	[thread overview]
Message-ID: <20200623133512.GA2783@bug> (raw)
In-Reply-To: <20200617101822.8558-1-andrzej.p@collabora.com>

Hi!

> +Inhibiting input devices
> +~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Inhibiting a device means ignoring input events from it. As such it is about maintaining
> +relationships with input handlers - either already existing relationships, or relationships
> +to be established while the device is in inhibited state.
> +
> +If a device is inhibited, no input handler will receive events from it.
> +
> +The fact that nobody wants events from the device is exploited further, by calling device's
> +close() (if there are users) and open() (if there are users) on inhibit and uninhibit
> +operations, respectively. Indeed, the meaning of close() is to stop providing events
> +to the input core and that of open() is to start providing events to the input core.
> +
> +Calling the device's close() method on inhibit (if there are users) allows the driver
> +to save power. Either by directly powering down the device or by releasing the
> +runtime-pm reference it got in open() when the driver is using runtime-pm.
> +
> +Inhibiting and uninhibiting are orthogonal to opening and closing the device by input
> +handlers. Userspace might want to inhibit a device in anticipation before any handler is
> +positively matched against it.

Ok.

> +Inhibiting and uninhibiting are orthogonal to device's being a wakeup source, too. 
> Being a +wakeup source plays a role when the system is sleeping, not when the system is 
> operating. +How drivers should program their interaction between inhibiting, sleeping 
> and being a wakeup +source is driver-specific. + +Taking the analogy with the network 

I don't believe making interaction driver-specific is good idea. We should decide
what reasonable behaviour is and then make drivers implement that...

Best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
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