linux-kernel - Re: [PATCH v6] 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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <1801397.7yxIcDsLaN@typ>
Date:	Wed, 15 Oct 2014 00:42:21 +0200
From:	Max Schwarz <max.schwarz@...ine.de>
To:	Addy Ke <addy.ke@...k-chips.com>
Cc:	wsa@...-dreams.de, heiko@...ech.de, olof@...om.net,
	dianders@...omium.org, linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, cf@...k-chips.com,
	xjq@...k-chips.com, huangtao@...k-chips.com, zyw@...k-chips.com,
	yzq@...k-chips.com, hj@...k-chips.com, kever.yang@...k-chips.com,
	hl@...k-chips.com, caesar.wang@...k-chips.com,
	zhengsq@...k-chips.com
Subject: Re: [PATCH v6] i2c: rk3x: adjust the LOW divison based on characteristics of SCL

Hi Addy,

On Tuesday 14 October 2014 at 14:09:21, Addy Ke wrote:
> As show in I2C specification:
> - Standard-mode: the minimum HIGH period of the scl clock is 4.0us
>                  the minimum LOW period of the scl clock is 4.7us
> - Fast-mode: the minimum HIGH period of the scl clock is 0.6us
>              the minimum LOW period of the scl clock is 1.3us
> 
> I have measured i2c SCL waveforms in fast-mode by oscilloscope
> on rk3288-pinky board. the LOW period of the scl clock is 1.3us.
> It is so critical that we must adjust LOW division to increase
> the LOW period of the scl clock.
> 
> Thanks Doug for the suggestion about division formulas.
> 
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Reviewed-by: Doug Anderson <dianders@...omium.org>
> Tested-by: Doug Anderson <dianders@...omium.org>
> Signed-off-by: Addy Ke <addy.ke@...k-chips.com>

Reviewed-by: Max Schwarz <max.schwarz@...ine.de>
Tested-by: Max Schwarz <max.schwarz@...ine.de>

Cheers,
  Max
--
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/