linux-kernel - Re: [PATCH] i2c: rk3x: adjust the LOW divison based on characteristics of SCL

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAD=FV=Uuk1zBYn4NgcpDSHVfKeyw3MONO7roUNVSPSDDEyD=8Q@mail.gmail.com>
Date:	Wed, 24 Sep 2014 21:36:38 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	addy ke <addy.ke@...k-chips.com>
Cc:	Wolfram Sang <wsa@...-dreams.de>,
	Max Schwarz <max.schwarz@...ine.de>,
	Heiko Stübner <heiko@...ech.de>,
	Olof Johansson <olof@...om.net>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-rockchip@...ts.infradead.org, Eddie Cai <cf@...k-chips.com>,
	Jianqun Xu <xjq@...k-chips.com>,
	Tao Huang <huangtao@...k-chips.com>,
	Chris <zyw@...k-chips.com>,
	姚智情 <yzq@...k-chips.com>,
	han jiang <hj@...k-chips.com>,
	Kever Yang <kever.yang@...k-chips.com>,
	Lin Huang <hl@...k-chips.com>,
	晓腾王 <caesar.wang@...k-chips.com>,
	Shunqian Zheng <zhengsq@...k-chips.com>
Subject: Re: [PATCH] i2c: rk3x: adjust the LOW divison based on
 characteristics of SCL

Addy,

On Wed, Sep 24, 2014 at 6:56 PM, addy ke <addy.ke@...k-chips.com> wrote:
> In my measurement,all paramter but "Data hold time" are match the characteristics of SCL bus line.
> the measured value is 0.928us("data hold time on RK3X"  ~=  "the low period / 2")
> but the maximum value described in table is 0.9us
>
> About "Data hold time", there are described in I2C specification:
> - for CBUS compatible masters for I2C-bus deivices
> - the maximum data hold time has only be met if the device does not stretch the LOW period of the SCL signal.
>
> I have tested on RK3288-Pinky board, there are no error.
> But I don't known whether this paramter will affect i2c communications.

I'll have to spend more time tomorrow to really understand this, but
if changing the code to bias towards slightly longer "high" times
instead of "low" times helps fix it then that's fine with me.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/