From: cheng wei Lin <dusonlin@emc.com.tw>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
bleung@chromium.org, agnescheng@chromium.org,
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<phoenix@emc.com.tw>,
jeff.chuang@emc.com.tw
Subject: Re: [PATCH v2] Input: add i2c/smbus driver for elan touchpad
Date: Sat, 26 Jul 2014 02:05:02 +0800 [thread overview]
Message-ID: <73E9FA09-55D6-409D-A902-29CC3F414CBF@emc.com.tw> (raw)
In-Reply-To: <20140724180516.GA26752@core.coreip.homeip.net>
Hi Dmitry,
Sorry for late to reply you and thanks for your command
Yes, I also agree, it looks great than my original code.
So, should I modify this and upstream v3 patch for you?
thank you,
duson
Dmitry Torokhov <dmitry.torokhov@gmail.com> 於 2014/7/25 上午2:05 寫道:
> Hi,
>
> On Tue, Jan 07, 2014 at 11:08:03AM +0800, Duson Lin wrote:
>> +/*
>> + ******************************************************************
>> + * General functions
>> + ******************************************************************
>> + */
>> +/*
>> + * (value from firmware) * 10 + 790 = dpi
>> + * we also have to convert dpi to dots/mm (*10/254 to avoid floating point)
>> + */
>> +static unsigned int elan_convert_res(char val)
>> +{
>> + int res;
>> + if (val & 0x80) {
>> + val = ~val + 1;
>> + res = (790 - val * 10) * 10 / 254;
>> + } else
>> + res = (val * 10 + 790) * 10 / 254;
>> + return res;
>> +}
>
> Why isn't this simply:
>
> res = ((int)val * 10 + 790) * 10 / 254;
>
> ?
>
> If high bit is 1 you basically do the 2 complement by hand to get to
> positive and then subtract. Which shoudl be the same as adding positive
> value.
>
> Thanks.
>
> --
> Dmitry
>
next prev parent reply other threads:[~2014-07-25 18:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-07 3:08 [PATCH v2] Input: add i2c/smbus driver for elan touchpad Duson Lin
2014-01-10 20:30 ` Benson Leung
2014-02-07 0:21 ` Benson Leung
2014-02-19 21:48 ` Benson Leung
2014-07-24 18:05 ` Dmitry Torokhov
2014-07-25 18:05 ` cheng wei Lin [this message]
2014-07-25 18:20 ` Dmitry Torokhov
2014-07-25 20:06 ` Dmitry Torokhov
2014-07-26 8:12 ` cheng wei Lin
2014-10-03 21:03 ` Dmitry Torokhov
2014-10-03 21:06 ` Dmitry Torokhov
2014-10-06 9:24 ` Mark Rutland
2014-10-06 16:37 ` Dmitry Torokhov
2014-10-03 21:30 ` Benson Leung
-- strict thread matches above, loose matches on Subject: below --
2013-12-18 3:46 Duson Lin
2014-02-07 0:10 ` Benson Leung
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