From: "Henrik Rydberg" <rydberg@euromail.se>
To: Daniel Kurtz <djkurtz@chromium.org>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
Jiri Kosina <jkosina@suse.cz>,
linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/19] Input: evdev - Add the events() callback
Date: Sat, 25 Aug 2012 21:46:16 +0200 [thread overview]
Message-ID: <20120825194616.GA4780@polaris.bitmath.org> (raw)
In-Reply-To: <CAGS+omCRsi=irbHXsDah48nOOMHYrNCCsnstCdqUTRvi=ZU99Q@mail.gmail.com>
> Reading the time just once and applying it as the timestamp to an
> entire frame is very nice.
> However, is it ever possible for the SYN_REPORT to get delayed until
> the next batch of input_values, therefore breaking the assumption that
> the SYN_REPORT timestamp applies to the rest of the input_values for
> its frame?
Yes, but see reply to previous patch.
> Also, bonus points if the input driver could set this input frame
> timestamp based on when it first saw a hardware interrupt rather then
> when evdev gets around to sending the frame to userspace. This could
> potentially remove a lot of the timing jitter userspace sees when
> computing ballistics based on input event timestamps.
In principle, yes (it has been discussed before), but in practise some
devices provide timestamps and some not, and the scale and granularity
may vary. In addition, desktop userland (read X input) does not even
use the kernel timestamp, so the effect would not even be seen without
a synchronized effort. I am not saying it is a bad idea, but it has
some details to get straight before it becomes useful.
Thanks,
Henrik
next prev parent reply other threads:[~2012-08-25 19:41 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-12 21:42 [PATCH 00/19] Input and HID updates for 3.7 Henrik Rydberg
2012-08-12 21:42 ` [PATCH 01/19] Input: Break out MT data Henrik Rydberg
2012-08-12 21:42 ` [PATCH 02/19] Input: Improve the events-per-packet estimate Henrik Rydberg
2012-08-14 19:32 ` Ping Cheng
2012-08-14 19:53 ` Dmitry Torokhov
2012-08-14 20:50 ` Ping Cheng
2012-08-14 21:12 ` Dmitry Torokhov
2012-08-15 0:54 ` Ping Cheng
2012-08-14 20:01 ` Henrik Rydberg
2012-08-14 21:06 ` Ping Cheng
2012-08-12 21:42 ` [PATCH 03/19] Input: Remove redundant packet estimates Henrik Rydberg
2012-08-12 21:42 ` [PATCH 04/19] Input: Make sure we follow all EV_KEY events Henrik Rydberg
2012-08-12 21:42 ` [PATCH 05/19] Input: Move autorepeat to the event-passing phase Henrik Rydberg
2012-08-12 21:42 ` [PATCH 06/19] Input: Send events one packet at a time Henrik Rydberg
2012-08-24 4:03 ` Daniel Kurtz
2012-08-25 19:38 ` Henrik Rydberg
2012-08-12 21:42 ` [PATCH 07/19] Input: evdev - Add the events() callback Henrik Rydberg
2012-08-24 4:07 ` Daniel Kurtz
2012-08-25 19:46 ` Henrik Rydberg [this message]
2012-08-12 21:42 ` [PATCH 08/19] Input: MT - Add flags to input_mt_init_slots() Henrik Rydberg
2012-08-12 21:42 ` [PATCH 09/19] Input: MT - Handle frame synchronization in core Henrik Rydberg
2012-08-15 23:28 ` Ping Cheng
2012-08-16 18:07 ` Henrik Rydberg
2012-08-16 19:22 ` Ping Cheng
2012-08-16 20:05 ` Henrik Rydberg
2012-08-16 19:58 ` Ping Cheng
2012-08-20 13:36 ` Benjamin Tissoires
2012-08-20 15:53 ` Henrik Rydberg
2012-08-12 21:42 ` [PATCH 10/19] Input: MT - Add in-kernel tracking Henrik Rydberg
2012-08-12 21:42 ` [PATCH 11/19] Input: MT - Add slot assignment by id Henrik Rydberg
2012-08-12 21:42 ` [PATCH 12/19] Input: bcm5974 - Preparatory renames Henrik Rydberg
2012-08-12 21:42 ` [PATCH 13/19] Input: bcm5974 - Drop pressure and width emulation Henrik Rydberg
2012-08-12 21:42 ` [PATCH 14/19] Input: bcm5974 - Drop the logical dimensions Henrik Rydberg
2012-08-12 21:42 ` [PATCH 15/19] Input: bcm5974 - Convert to MT-B Henrik Rydberg
2012-08-12 21:42 ` [PATCH 16/19] HID: hid-multitouch: Remove misleading null test Henrik Rydberg
2012-08-20 13:35 ` Benjamin Tissoires
2012-08-12 21:42 ` [PATCH 17/19] HID: Only dump input if someone is listening Henrik Rydberg
2012-08-12 21:42 ` [PATCH 18/19] HID: Add an input configured notification callback Henrik Rydberg
2012-08-12 21:42 ` [PATCH 19/19] HID: multitouch: Remove the redundant touch state Henrik Rydberg
2012-08-20 13:36 ` Benjamin Tissoires
2012-08-20 16:01 ` Henrik Rydberg
2012-08-22 20:58 ` [PATCH v2] " Henrik Rydberg
2012-08-28 22:25 ` Jiri Kosina
2012-08-29 13:36 ` Benjamin Tissoires
2012-08-29 17:18 ` Jiri Kosina
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