From patchwork Wed May 27 14:54:46 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Koskinen, Aaro (Nokia - FI/Espoo)" X-Patchwork-Id: 26488 X-Patchwork-Delegate: tony@atomide.com Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n4REssjv011222 for ; Wed, 27 May 2009 14:54:55 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762394AbZE0Oyv (ORCPT ); Wed, 27 May 2009 10:54:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761159AbZE0Oyu (ORCPT ); Wed, 27 May 2009 10:54:50 -0400 Received: from smtp.nokia.com ([192.100.105.134]:24891 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751503AbZE0Oyu (ORCPT ); Wed, 27 May 2009 10:54:50 -0400 Received: from vaebh105.NOE.Nokia.com (vaebh105.europe.nokia.com [10.160.244.31]) by mgw-mx09.nokia.com (Switch-3.2.6/Switch-3.2.6) with ESMTP id n4REsSUb002744; Wed, 27 May 2009 09:54:52 -0500 Received: from vaebh104.NOE.Nokia.com ([10.160.244.30]) by vaebh105.NOE.Nokia.com with Microsoft SMTPSVC(6.0.3790.3959); Wed, 27 May 2009 17:54:47 +0300 Received: from mgw-sa02.ext.nokia.com ([147.243.1.48]) by vaebh104.NOE.Nokia.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Wed, 27 May 2009 17:54:47 +0300 Received: from localhost.localdomain (esdhcp043221.research.nokia.com [172.21.43.221]) by mgw-sa02.ext.nokia.com (Switch-3.2.6/Switch-3.2.6) with ESMTP id n4REskmw017321; Wed, 27 May 2009 17:54:47 +0300 From: Aaro Koskinen To: linux-i2c@vger.kernel.org, linux-omap@vger.kernel.org Subject: [PATCH 2/2] I2C: OMAP3: Better noise suppression for fast/standard modes Date: Wed, 27 May 2009 17:54:46 +0300 Message-Id: <1243436086-3623-2-git-send-email-aaro.koskinen@nokia.com> X-Mailer: git-send-email 1.5.4.3 In-Reply-To: <1243436086-3623-1-git-send-email-aaro.koskinen@nokia.com> References: <> <1243436086-3623-1-git-send-email-aaro.koskinen@nokia.com> X-OriginalArrivalTime: 27 May 2009 14:54:47.0515 (UTC) FILETIME=[14376AB0:01C9DEDB] X-Nokia-AV: Clean Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org Use longer noise filter period for fast and standard mode. Based on an earlier patch by Eero Nurkkala. Signed-off-by: Aaro Koskinen Acked-by: Tony Lindgren --- drivers/i2c/busses/i2c-omap.c | 14 ++++++++++++-- 1 files changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 5d9880c..8c76cea 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -333,8 +333,18 @@ static int omap_i2c_init(struct omap_i2c_dev *dev) if (cpu_is_omap2430() || cpu_is_omap34xx()) { - /* HSI2C controller internal clk rate should be 19.2 Mhz */ - internal_clk = 19200; + /* + * HSI2C controller internal clk rate should be 19.2 Mhz for + * HS and for all modes on 2430. On 34xx we can use lower rate + * to get longer filter period for better noise suppression. + * The filter is iclk (fclk for HS) period. + */ + if (dev->speed > 400 || cpu_is_omap_2430()) + internal_clk = 19200; + else if (dev->speed > 100) + internal_clk = 9600; + else + internal_clk = 4000; fclk_rate = clk_get_rate(dev->fclk) / 1000; /* Compute prescaler divisor */