From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752779AbbDACL1 (ORCPT ); Tue, 31 Mar 2015 22:11:27 -0400 Received: from mailgw01.mediatek.com ([210.61.82.183]:53915 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751910AbbDACLY (ORCPT ); Tue, 31 Mar 2015 22:11:24 -0400 X-Listener-Flag: 11101 Subject: Re: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller From: Eddie Huang To: Sascha Hauer CC: Mark Rutland , Wolfram Sang , Doug Anderson , "linux-i2c@vger.kernel.org" , David Box , Lee Jones , Jean Delvare , Xudong Chen =?UTF-8?Q?=28=E9=99=88=E6=97=AD=E4=B8=9C=29?= , Boris BREZILLON , Pawel Moll , Liguo Zhang =?UTF-8?Q?=28=E5=BC=A0=E7=AB=8B=E5=9B=BD=29?= , Wei Yan , Bjorn Andersson , Uwe Kleine-Konig , Neelesh Gupta , "devicetree@vger.kernel.org" , Arnd Bergmann , Ian Campbell , Beniamino Galvani , Rob Herring , "linux-mediatek@lists.infradead.org" , Matthias Brugger , "linux-arm-kernel@lists.infradead.org" , srv_heupstream , Anders Berg , Jim Cromie , Simon Glass , Max Schwarz , "linux-kernel@vger.kernel.org" , Sascha Hauer , Kumar Gala In-Reply-To: <20150331175234.GK9742@pengutronix.de> References: <1426917922-61356-1-git-send-email-eddie.huang@mediatek.com> <1426917922-61356-3-git-send-email-eddie.huang@mediatek.com> <20150323084237.GG9742@pengutronix.de> <1427703252.26464.14.camel@mtksdaap41> <20150330172309.GB9742@pengutronix.de> <1427785715.3500.16.camel@mtksdaap41> <1427802658.32196.8.camel@mtksdaap41> <20150331175234.GK9742@pengutronix.de> Content-Type: text/plain; charset="UTF-8" Date: Wed, 1 Apr 2015 10:11:17 +0800 Message-ID: <1427854277.21285.15.camel@mtksdaap41> MIME-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sascha, On Tue, 2015-03-31 at 19:52 +0200, Sascha Hauer wrote: > On Tue, Mar 31, 2015 at 07:50:58PM +0800, Eddie Huang wrote: > > Hi Sascha, > > > > On Tue, 2015-03-31 at 15:08 +0800, Eddie Huang wrote: > > > Hi Sascha, > > > > > > > > > speed <= 400000 here to make this more obvious? > > > > > There are two cases, not only speed<=400000, but I2C_MASTER_WRRD. I tend > > > > > to keep it. > > > > > > > > Still it looks strange. You only ever write this default value to the > > > > register. Putting this register write under an if() seems bogus since > > > > the same value will be in the register the next time this code is > > > > executed. It looks like you should move this register write to some > > > > initialization function. > > > OK, move to mtk_i2c_init_hw function > > > > > Sorry for my negligence. Write-then-read (I2C_MASTER_WRRD) decides > > according to each I2C transfer, so I still need to judge whether set > > I2C_CONTROL_RS and DELAY_LEN here. Other control setting can move to > > init function. > > You need to decide whether you have to set the I2C_CONTROL_RS bit, but > you don't need to write the same value to the DELAY_LEN register each > time. It won't change under your hood. > Yes, you are right. DELAY_LEN should only be set one time in init function. Thanks your correction. Eddie From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eddie Huang Subject: Re: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller Date: Wed, 1 Apr 2015 10:11:17 +0800 Message-ID: <1427854277.21285.15.camel@mtksdaap41> References: <1426917922-61356-1-git-send-email-eddie.huang@mediatek.com> <1426917922-61356-3-git-send-email-eddie.huang@mediatek.com> <20150323084237.GG9742@pengutronix.de> <1427703252.26464.14.camel@mtksdaap41> <20150330172309.GB9742@pengutronix.de> <1427785715.3500.16.camel@mtksdaap41> <1427802658.32196.8.camel@mtksdaap41> <20150331175234.GK9742@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150331175234.GK9742-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sascha Hauer Cc: Mark Rutland , Wolfram Sang , Doug Anderson , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , David Box , Lee Jones , Jean Delvare , Xudong Chen =?UTF-8?Q?=28=E9=99=88=E6=97=AD=E4=B8=9C=29?= , Boris BREZILLON , Pawel Moll , Liguo Zhang =?UTF-8?Q?=28=E5=BC=A0=E7=AB=8B=E5=9B=BD=29?= , Wei Yan , Bjorn Andersson , Uwe Kleine-Konig , Neelesh Gupta , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Arnd Bergmann , Ian Campbell , Beniamino Galvani List-Id: devicetree@vger.kernel.org Hi Sascha, On Tue, 2015-03-31 at 19:52 +0200, Sascha Hauer wrote: > On Tue, Mar 31, 2015 at 07:50:58PM +0800, Eddie Huang wrote: > > Hi Sascha, > > > > On Tue, 2015-03-31 at 15:08 +0800, Eddie Huang wrote: > > > Hi Sascha, > > > > > > > > > speed <= 400000 here to make this more obvious? > > > > > There are two cases, not only speed<=400000, but I2C_MASTER_WRRD. I tend > > > > > to keep it. > > > > > > > > Still it looks strange. You only ever write this default value to the > > > > register. Putting this register write under an if() seems bogus since > > > > the same value will be in the register the next time this code is > > > > executed. It looks like you should move this register write to some > > > > initialization function. > > > OK, move to mtk_i2c_init_hw function > > > > > Sorry for my negligence. Write-then-read (I2C_MASTER_WRRD) decides > > according to each I2C transfer, so I still need to judge whether set > > I2C_CONTROL_RS and DELAY_LEN here. Other control setting can move to > > init function. > > You need to decide whether you have to set the I2C_CONTROL_RS bit, but > you don't need to write the same value to the DELAY_LEN register each > time. It won't change under your hood. > Yes, you are right. DELAY_LEN should only be set one time in init function. Thanks your correction. Eddie From mboxrd@z Thu Jan 1 00:00:00 1970 From: eddie.huang@mediatek.com (Eddie Huang) Date: Wed, 1 Apr 2015 10:11:17 +0800 Subject: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller In-Reply-To: <20150331175234.GK9742@pengutronix.de> References: <1426917922-61356-1-git-send-email-eddie.huang@mediatek.com> <1426917922-61356-3-git-send-email-eddie.huang@mediatek.com> <20150323084237.GG9742@pengutronix.de> <1427703252.26464.14.camel@mtksdaap41> <20150330172309.GB9742@pengutronix.de> <1427785715.3500.16.camel@mtksdaap41> <1427802658.32196.8.camel@mtksdaap41> <20150331175234.GK9742@pengutronix.de> Message-ID: <1427854277.21285.15.camel@mtksdaap41> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Sascha, On Tue, 2015-03-31 at 19:52 +0200, Sascha Hauer wrote: > On Tue, Mar 31, 2015 at 07:50:58PM +0800, Eddie Huang wrote: > > Hi Sascha, > > > > On Tue, 2015-03-31 at 15:08 +0800, Eddie Huang wrote: > > > Hi Sascha, > > > > > > > > > speed <= 400000 here to make this more obvious? > > > > > There are two cases, not only speed<=400000, but I2C_MASTER_WRRD. I tend > > > > > to keep it. > > > > > > > > Still it looks strange. You only ever write this default value to the > > > > register. Putting this register write under an if() seems bogus since > > > > the same value will be in the register the next time this code is > > > > executed. It looks like you should move this register write to some > > > > initialization function. > > > OK, move to mtk_i2c_init_hw function > > > > > Sorry for my negligence. Write-then-read (I2C_MASTER_WRRD) decides > > according to each I2C transfer, so I still need to judge whether set > > I2C_CONTROL_RS and DELAY_LEN here. Other control setting can move to > > init function. > > You need to decide whether you have to set the I2C_CONTROL_RS bit, but > you don't need to write the same value to the DELAY_LEN register each > time. It won't change under your hood. > Yes, you are right. DELAY_LEN should only be set one time in init function. Thanks your correction. Eddie