From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: Re: tHigh tLow discussion (was [pacth] I2C bug fixes for L-O and L-Z) Date: Tue, 24 Feb 2009 13:43:14 +0200 Message-ID: <49A3DD52.4020303@gmail.com> References: <1234767724.16827.7.camel@eenurkka-desktop> <13B9B4C6EF24D648824FF11BE896716203771DC940@dlee02.ent.ti.com> <1234850560.13109.9.camel@eenurkka-desktop> <13B9B4C6EF24D648824FF11BE896716203771DD194@dlee02.ent.ti.com> <13B9B4C6EF24D648824FF11BE896716203772C3CAF@dlee02.ent.ti.com> <1235396273.12653.8.camel@eenurkka-desktop> <49A2D66F.9050809@gmail.com> <1FFEF31EBAA4F64B80D33027D4297760036DEC2F6F@NOK-EUMSG-02.mgdnok.nokia.com> <782515bb0902231019l17eaef2crfcb6426fbbbf8d04@mail.gmail.com> <49A3B92E.9030101@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-fx0-f167.google.com ([209.85.220.167]:34338 "EHLO mail-fx0-f167.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751048AbZBXLnT (ORCPT ); Tue, 24 Feb 2009 06:43:19 -0500 Received: by fxm11 with SMTP id 11so2686340fxm.13 for ; Tue, 24 Feb 2009 03:43:16 -0800 (PST) In-Reply-To: <49A3B92E.9030101@nokia.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Aaro Koskinen Cc: "Nurkkala Eero.An (EXT-Offcode/Oulu)" , "r-woodruff2@ti.com" , "linux-omap@vger.kernel.org" Aaro Koskinen said the following on 02/24/2009 11:09 AM: > ext Nishanth Menon wrote: >> Oops.. copy-paste typo.. :( >> tLow = (scll+3) * iclk >> tHigh = (sclh+9) * iclk >> Vs: >> TRM: >> tHigh = ( sclh +5 )*iclk period >> tLow = ( scll +7 )*iclk period >> >> But my question is this: why are we trying to a different equation >> here compared to the equation in the TRM? > > The problem with TRM (the table 18-13 you referred earlier) is that it > assumes 50% duty cycle while the correct one is more like 33%. This is > corrected by Eero's patch: Gentle query - could you point me to the place where the 33% duty cycle is mentioned in i2c spec? spec mentions minimum timing, but I don't seem to find a constraint on duty cycle requirement.. :( Regards, Nishanth Menon