Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758134AbcDMMVO (ORCPT ); Wed, 13 Apr 2016 08:21:14 -0400 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:58705 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753378AbcDMMVN (ORCPT ); Wed, 13 Apr 2016 08:21:13 -0400 Date: Wed, 13 Apr 2016 20:16:37 +0800 From: Jisheng Zhang To: Andy Shevchenko CC: Wolfram Sang , Rob Herring , Pawel Moll , Mark Rutland , ijc+devicetree , Kumar Gala , Jarkko Nikula , "Andy Shevchenko" , Mika Westerberg , , devicetree , "linux-kernel@vger.kernel.org" , linux-arm Mailing List Subject: Re: [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT Message-ID: <20160413201637.284a3673@xhacker> In-Reply-To: References: <1459927680-5480-1-git-send-email-jszhang@marvell.com> X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-04-13_08:,, signatures=0 X-Proofpoint-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1603180000 definitions=main-1604130178 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3822 Lines: 84 Dear Andy, On Thu, 7 Apr 2016 21:05:35 +0300 Andy Shevchenko wrote: > On Wed, Apr 6, 2016 at 10:28 AM, Jisheng Zhang wrote: > > Sometimes, it's convenient to define the scl's high/low count directly, > > e.g HW people would do some measurement then directly give out the > > optimum counts. Previously, we solved the sda falling time and scl > > falling time by i2c_dw_scl_hcnt() and i2c_dw_scl_lcnt(), then put them > > into dt, but what we really care isn't the sda/scl falling time. > > > > From another side, the dw_i2c_acpi_configure() on ACPI platform also > > get hcnt/lcnt values rather than the sda/scl falling time from ACPI > > method, we want similar feature for DT platforms. > > > > Instead of duplicating some words maybe better to explicitly define > two groups of parameters and one which supersedes the other. I'm sorry, I can't catch your meaning. Could you please kindly give more details? Or examples of "two groups of parameters" Thanks, Jisheng > > > Signed-off-by: Jisheng Zhang > > --- > > Documentation/devicetree/bindings/i2c/i2c-designware.txt | 16 ++++++++++++++++ > > drivers/i2c/busses/i2c-designware-platdrv.c | 8 ++++++++ > > 2 files changed, 24 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > index fee26dc..05176fbf 100644 > > --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt > > @@ -20,6 +20,22 @@ Optional properties : > > - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds. > > This value which is by default 300ns is used to compute the tHIGH period. > > > > + - i2c-ss-scl-high-count : should contain the standard speed i2c clock SCL high > > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns > > + will be ignored. > > + > > + - i2c-ss-scl-low-count : should contain the standard speed i2c clock SCL low > > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns > > + will be ignored. > > + > > + - i2c-fs-scl-high-count : should contain the fast speed i2c clock SCL high > > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns > > + will be ignored. > > + > > + - i2c-fs-scl-low-count : should contain the fast speed i2c clock SCL low > > + count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns > > + will be ignored. > > + > > Example : > > > > i2c@f0000 { > > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c > > index d656657..8739a60 100644 > > --- a/drivers/i2c/busses/i2c-designware-platdrv.c > > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c > > @@ -188,6 +188,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev) > > &dev->scl_falling_time); > > device_property_read_u32(&pdev->dev, "clock-frequency", > > &clk_freq); > > + device_property_read_u16(&pdev->dev, "i2c-ss-scl-high-count", > > + &dev->ss_hcnt); > > + device_property_read_u16(&pdev->dev, "i2c-ss-scl-low-count", > > + &dev->ss_lcnt); > > + device_property_read_u16(&pdev->dev, "i2c-fs-scl-high-count", > > + &dev->fs_hcnt); > > + device_property_read_u16(&pdev->dev, "i2c-fs-scl-low-count", > > + &dev->fs_lcnt); > > } > > > > if (has_acpi_companion(&pdev->dev)) > > -- > > 2.8.0.rc3 > > > > >