Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760812AbcDMNW6 (ORCPT ); Wed, 13 Apr 2016 09:22:58 -0400 Received: from mga01.intel.com ([192.55.52.88]:54747 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758369AbcDMNWy (ORCPT ); Wed, 13 Apr 2016 09:22:54 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,479,1455004800"; d="scan'208";a="957766956" Message-ID: <1460553825.6620.134.camel@linux.intel.com> Subject: Re: [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT From: Andy Shevchenko To: Jisheng Zhang , Andy Shevchenko Cc: Wolfram Sang , Rob Herring , Pawel Moll , Mark Rutland , ijc+devicetree , Kumar Gala , Jarkko Nikula , Mika Westerberg , linux-i2c@vger.kernel.org, devicetree , "linux-kernel@vger.kernel.org" , linux-arm Mailing List Date: Wed, 13 Apr 2016 16:23:45 +0300 In-Reply-To: <20160413201637.284a3673@xhacker> References: <1459927680-5480-1-git-send-email-jszhang@marvell.com> <20160413201637.284a3673@xhacker> Organization: Intel Finland Oy Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.5.1-1 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4028 Lines: 106 On Wed, 2016-04-13 at 20:16 +0800, Jisheng Zhang wrote: > 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" > --- + - 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. I'm referring to the above sentence. Something like There are two groups of values identifying i2c timings: 1. i2c-scl-falling-time-ns and i2c-sda-falling-time-ns 2. *-[hl]cnt The second group of parameters supersedes the first one. > > > + > > > + - 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 > > >   > > > > -- Andy Shevchenko Intel Finland Oy