From: "Éric Piel" <E.A.B.Piel@tudelft.nl>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: JJ Ding <jj_ding@emc.com.tw>,
linux-input@vger.kernel.org, Tom Lin <tom_lin@emc.com.tw>,
Aaron Huang <aaron_huang@emc.com.tw>,
Daniel Kurtz <djkurtz@chromium.org>
Subject: Re: [PATCH] Input: elantech - correct x, y value range for v2 hardware
Date: Wed, 17 Aug 2011 11:53:55 +0200 [thread overview]
Message-ID: <4E4B8FB3.9090100@tudelft.nl> (raw)
In-Reply-To: <20110817064336.GA29361@core.coreip.homeip.net>
Op 17-08-11 08:43, Dmitry Torokhov schreef:
> Hi JJ,
>
>> As far as I know, this doesn't fix a bug. I just want to make sure the
>> driver and what the firmware sends are consistent.
>
> As Éric mentioned, simply extending range to 12 bits is dangerous
> because we might cause overflows. Blindly increasing ETP_YMAX_V2 is not
> a good idea either as userspace would expect much larger device and
> reports would only cover fraction of its surface. We need to separate
> ETP_YMAX_V2 as absolute maximum from reported coordinates range, like it
> is done in synaptics driver.
Hi Dmitry,
Concerning this point, I was wondering if it'd be ok to only send
negative values? Such as min/max are between -768 and 0. So that, if the
hardware actually has a bigger resolution, it can go down to -4095
without any overflow? It sounds the simplest way to report the
coordinate for a device which has an opposite axis. Or is it safer to
stay in the positive numbers, with min/max between 3328 and 4095, and in
case of bigger resolution the values go down to 0?
Cheers,
Éric
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next prev parent reply other threads:[~2011-08-17 9:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-15 3:51 [PATCH] Input: elantech - correct x, y value range for v2 hardware JJ Ding
2011-08-15 5:25 ` Daniel Kurtz
2011-08-15 12:45 ` Éric Piel
2011-08-16 1:12 ` JJ Ding
2011-08-16 11:11 ` JJ Ding
2011-08-16 21:50 ` Éric Piel
2011-08-17 1:28 ` JJ Ding
2011-08-17 6:43 ` Dmitry Torokhov
2011-08-17 9:53 ` Éric Piel [this message]
2011-08-17 16:37 ` Dmitry Torokhov
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