From mboxrd@z Thu Jan 1 00:00:00 1970 From: ext-eero.nurkkala@nokia.com Subject: [PATCH] i2c: i2c-omap: Fix standard and fast mode prescalers Date: Tue, 11 Nov 2008 08:52:32 +0200 Message-ID: <12263863521940-git-send-email-ext-eero.nurkkala@nokia.com> Return-path: Received: from smtp.nokia.com ([192.100.122.233]:39779 "EHLO mgw-mx06.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752031AbYKKGyn (ORCPT ); Tue, 11 Nov 2008 01:54:43 -0500 Received: from esebh105.NOE.Nokia.com (esebh105.ntc.nokia.com [172.21.138.211]) by mgw-mx06.nokia.com (Switch-3.2.6/Switch-3.2.6) with ESMTP id mAB6rkew030828 for ; Tue, 11 Nov 2008 08:53:54 +0200 Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: linux-omap@vger.kernel.org Cc: Eero Nurkkala From: Eero Nurkkala The prescalers for 100 kHz and 400 kHz mode are wrong. The internal clock is the fclock divided by the prescaler. Also, the scll and sclh values should be adjusted correctly. Having the correct prescaler is important in the process of getting standard i2c clock. In addition, it (psc) is used to get the correct noise filter and thus, lets more error resilient i2c communications. Signed-off-by: Eero Nurkkala --- drivers/i2c/busses/i2c-omap.c | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index f15668d..cee2f2d 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -288,7 +288,13 @@ 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; + if (dev->speed > 400) + 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 */ @@ -306,8 +312,8 @@ static int omap_i2c_init(struct omap_i2c_dev *dev) hssclh = fclk_rate / (dev->speed * 2) - 6; } else { /* To handle F/S modes */ - fsscll = internal_clk / (dev->speed * 2) - 6; - fssclh = internal_clk / (dev->speed * 2) - 6; + fsscll = internal_clk / (dev->speed * 2) - 7; + fssclh = internal_clk / (dev->speed * 2) - 5; } scll = (hsscll << OMAP_I2C_SCLL_HSSCLL) | fsscll; sclh = (hssclh << OMAP_I2C_SCLH_HSSCLH) | fssclh; -- 1.6.0