linux-kernel - Re: [PATCH v2 1/4] uinput: Add ioctl for using monotonic/ boot times

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Date:   Fri, 28 Oct 2016 14:32:57 +1000
From:   Peter Hutterer <peter.hutterer@...-t.net>
To:     Deepa Dinamani <deepa.kernel@...il.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        y2038 Mailman List <y2038@...ts.linaro.org>
Subject: Re: [PATCH v2 1/4] uinput: Add ioctl for using monotonic/ boot times

On Thu, Oct 27, 2016 at 01:39:30PM -0700, Deepa Dinamani wrote:
> > hmm, I'm a bit confused here. This is an in-kernel bit only (passing the
> > time through uinput events has no effect). So why do we need an ioctl here?
> > it's an in-kernel decision only anyway and the time in the events sent to
> > the evdev client should be dictated by what that client sets for the clock
> > type, right?
> 
> This is for input events queued by the uinput driver for the virtual
> input device.

oh, right. I thought this was in the path for uinput_write(). sorry about
that.

> This can be read through uinput_read() fops.
> I don't think anybody is doing a read on uinput nodes, so another
> option(Arnd and I considered this) could be not supporting reads on
> these nodes at all.
> 
> This is not related to evdev events in the kernel.
> Currently, this timestamp could be the same format as the evdev
> timestamps or not.

I can say I've never done the read from the uinput device, never even
occured to me. quick skim of the code looks like this only matters for
force_feedback stuff. can't really comment on that too much.

Cheers,
   Peter