From patchwork Mon Apr 26 09:01:45 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thomas.koeller@baslerweb.com X-Patchwork-Id: 95023 Received: from lists.sourceforge.net (lists.sourceforge.net [216.34.181.88]) by demeter.kernel.org (8.14.3/8.14.3) with ESMTP id o3Q9Gged001434 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 26 Apr 2010 09:17:19 GMT Received: from localhost ([127.0.0.1] helo=sfs-ml-3.v29.ch3.sourceforge.com) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.69) (envelope-from ) id 1O6KQh-0007f6-Jl; Mon, 26 Apr 2010 09:16:39 +0000 Received: from sfi-mx-2.v28.ch3.sourceforge.com ([172.29.28.122] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.69) (envelope-from ) id 1O6KQg-0007f1-9d for spi-devel-general@lists.sourceforge.net; Mon, 26 Apr 2010 09:16:38 +0000 X-ACL-Warn: Received: from mail01.baslerweb.com ([80.156.24.166]) by sfi-mx-2.v28.ch3.sourceforge.com with esmtp (Exim 4.69) id 1O6KQd-0004EI-P4 for spi-devel-general@lists.sourceforge.net; Mon, 26 Apr 2010 09:16:38 +0000 Received: from unknown (HELO AHR075S.basler.corp) ([172.16.20.75]) by mail01-out.baslerweb.com with ESMTP; 26 Apr 2010 11:05:11 +0200 Received: from localhost.localdomain ([172.16.13.131]) by AHR075S.basler.corp with Microsoft SMTPSVC(6.0.3790.4675); Mon, 26 Apr 2010 11:05:06 +0200 From: thomas.koeller@baslerweb.com To: davinci-linux-open-source@linux.davinci.com, spi-devel-general@lists.sourceforge.net Date: Mon, 26 Apr 2010 11:01:45 +0200 Message-Id: <1272272505-5021-2-git-send-email-thomas.koeller@baslerweb.com> X-Mailer: git-send-email 1.7.0.3 In-Reply-To: <871veaksca.fsf@deeprootsystems.com> References: <871veaksca.fsf@deeprootsystems.com> In-Reply-To: <871veaksca.fsf@deeprootsystems.com> References: <871veaksca.fsf@deeprootsystems.com> X-OriginalArrivalTime: 26 Apr 2010 09:05:06.0239 (UTC) FILETIME=[905F44F0:01CAE51F] X-Spam-Score: 0.0 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. _SUMMARY_ X-Headers-End: 1O6KQd-0004EI-P4 Cc: Sudhakar Rajashekhara , Kevin Hilman , Thomas Koeller , Sandeep Paulraj , Philby John Subject: [spi-devel-general] [PATCH] DaVinci SPI: Fix SPI clock prescale factor computation X-BeenThere: spi-devel-general@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: Linux SPI core/device drivers discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: spi-devel-general-bounces@lists.sourceforge.net X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.3 (demeter.kernel.org [140.211.167.41]); Mon, 26 Apr 2010 09:17:19 +0000 (UTC) diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c index 956f617..02e1a76 100644 --- a/drivers/spi/davinci_spi.c +++ b/drivers/spi/davinci_spi.c @@ -153,7 +153,7 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, struct davinci_spi *davinci_spi; struct davinci_spi_platform_data *pdata; u8 bits_per_word = 0; - u32 hz = 0, prescale; + u32 hz = 0, prescale = 0, clkspeed; davinci_spi = spi_master_get_devdata(spi->master); pdata = davinci_spi->pdata; @@ -190,10 +190,16 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, set_fmt_bits(davinci_spi->base, bits_per_word & 0x1f, spi->chip_select); - prescale = ((clk_get_rate(davinci_spi->clk) / hz) - 1) & 0xff; + clkspeed = clk_get_rate(davinci_spi->clk); + if (hz > clkspeed / 2) + prescale = 1 << 8; + if (hz < clkspeed / 256) + prescale = 255 << 8; + if (!prescale) + prescale = ((clkspeed / hz - 1) << 8) & 0x0000ff00; clear_fmt_bits(davinci_spi->base, 0x0000ff00, spi->chip_select); - set_fmt_bits(davinci_spi->base, prescale << 8, spi->chip_select); + set_fmt_bits(davinci_spi->base, prescale, spi->chip_select); return 0; }