From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751738AbaHTOiP (ORCPT ); Wed, 20 Aug 2014 10:38:15 -0400 Received: from mail-bn1lp0142.outbound.protection.outlook.com ([207.46.163.142]:53451 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750942AbaHTOiN (ORCPT ); Wed, 20 Aug 2014 10:38:13 -0400 Date: Wed, 20 Aug 2014 09:32:49 -0500 From: atull X-X-Sender: atull@atx-linux-37 To: Romain Baeriswyl CC: Wolfram Sang , Mika Westerberg , Christian Ruppert , "Rafael J. Wysocki" , , , Mark Rutland , , , , , , , , , , Romain Baeriswyl Subject: Re: [PATCH] i2c designware add support of I2C standard mode In-Reply-To: <1408544948-22339-1-git-send-email-romainba@abilis.com> Message-ID: References: <20140820124231.GD21734@leverpostej> <1408544948-22339-1-git-send-email-romainba@abilis.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-Originating-IP: [64.129.157.38] X-ClientProxiedBy: CO1PR06CA039.namprd06.prod.outlook.com (10.242.160.29) To BY2PR03MB316.namprd03.prod.outlook.com (10.141.139.26) X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:;UriScan:; X-Forefront-PRVS: 03094A4065 X-Forefront-Antispam-Report: SFV:NSPM;SFS:(6009001)(51704005)(199003)(24454002)(189002)(64706001)(23726002)(20776003)(47776003)(4396001)(42186005)(79102001)(102836001)(21056001)(53416004)(66066001)(80022001)(46102001)(86152002)(86362001)(85306004)(92566001)(77982001)(69596002)(83506001)(19580395003)(19580405001)(76176999)(46406003)(50466002)(92726001)(54356999)(76482001)(85852003)(74662001)(50986999)(99396002)(81542001)(31966008)(81156004)(81342001)(83322001)(101416001)(105586002)(77096002)(33716001)(83072002)(106356001)(107046002)(74502001)(95666004)(87976001)(110136001);DIR:OUT;SFP:;SCL:1;SRVR:BY2PR03MB316;H:atx-linux-37.altera.com;FPR:;MLV:sfv;PTR:InfoNoRecords;A:0;MX:1;LANG:en; X-OriginatorOrg: opensource.altera.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 20 Aug 2014, Romain Baeriswyl wrote: > From: Romain Baeriswyl > > Some legacy devices support ony I2C standard mode at 100kHz. > This patch allows to select the standard mode through the DTS > with the use of the existing clock-frequency parameter. > > When clock-frequency parameter is not set, the fast mode is selected. > Only when the parameter is set at 100000, the standard mode is selected. > > Signed-off-by: Romain Baeriswyl > Reviewed-by: Christian Ruppert > --- > drivers/i2c/busses/i2c-designware-platdrv.c | 23 +++++++++++++++++++++-- > 1 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > index 402ec39..b543fe1 100644 > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > @@ -122,6 +122,7 @@ static int dw_i2c_probe(struct platform_device *pdev) > struct i2c_adapter *adap; > struct resource *mem; > int irq, r; > + u32 clk_freq; > > irq = platform_get_irq(pdev, 0); > if (irq < 0) { > @@ -151,6 +152,9 @@ static int dw_i2c_probe(struct platform_device *pdev) > return PTR_ERR(dev->clk); > clk_prepare_enable(dev->clk); > > + /* fast mode by default because of legacy reasons */ > + clk_freq = 400000; > + > if (pdev->dev.of_node) { > u32 ht = 0; > u32 ic_clk = dev->get_clk_rate_khz(dev); > @@ -166,6 +170,17 @@ static int dw_i2c_probe(struct platform_device *pdev) > of_property_read_u32(pdev->dev.of_node, > "i2c-scl-falling-time-ns", > &dev->scl_falling_time); > + > + of_property_read_u32(pdev->dev.of_node, "clock-frequency", > + &clk_freq); > + > + /* Only standard mode at 100kHz and fast mode at 400kHz > + * are supported. > + */ > + if (clk_freq != 100000 && clk_freq != 400000) { > + dev_err(&pdev->dev, "Only 100kHz and 400kHz supported"); > + return -EINVAL; > + } Hi Romain, It is common to operate i2c at <100KHz on boards that have i2c issues. I am using this driver at 50KHz because I have a LCD module that just doesn't work at a full 100KHz. Please remove the check for these two frequency points. > } > > dev->functionality = > @@ -175,8 +190,12 @@ static int dw_i2c_probe(struct platform_device *pdev) > I2C_FUNC_SMBUS_BYTE_DATA | > I2C_FUNC_SMBUS_WORD_DATA | > I2C_FUNC_SMBUS_I2C_BLOCK; > - dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | > - DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST; > + if (clk_freq == 100000) Please change to <= > + dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | > + DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_STD; > + else > + dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | > + DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST; > > /* Try first if we can configure the device from ACPI */ > r = dw_i2c_acpi_configure(pdev); > -- > 1.7.1 > >