From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753322AbbCaRxf (ORCPT ); Tue, 31 Mar 2015 13:53:35 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:50604 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753064AbbCaRxd (ORCPT ); Tue, 31 Mar 2015 13:53:33 -0400 Date: Tue, 31 Mar 2015 19:52:34 +0200 From: Sascha Hauer To: Eddie Huang Cc: Mark Rutland , Wolfram Sang , Doug Anderson , "linux-i2c@vger.kernel.org" , David Box , Lee Jones , Jean Delvare , Xudong Chen =?utf-8?B?KOmZiOaXreS4nCk=?= , Boris BREZILLON , Pawel Moll , Liguo Zhang =?utf-8?B?KOW8oOeri+WbvSk=?= , 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 Subject: Re: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller Message-ID: <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427802658.32196.8.camel@mtksdaap41> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 19:49:41 up 15 days, 5:41, 53 users, load average: 0.19, 0.14, 0.11 User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: sha@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Subject: Re: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller Date: Tue, 31 Mar 2015 19:52:34 +0200 Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1427802658.32196.8.camel@mtksdaap41> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eddie Huang Cc: Mark Rutland , Wolfram Sang , Doug Anderson , "linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , David Box , Lee Jones , Jean Delvare , Xudong Chen =?utf-8?B?KOmZiOaXreS4nCk=?= , Boris BREZILLON , Pawel Moll , Liguo Zhang =?utf-8?B?KOW8oOeri+WbvSk=?= , Wei Yan , Bjorn Andersson , Uwe Kleine-Konig , Neelesh Gupta , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Arnd Bergmann , Ian Campbell , Beniamino Galvani , Rob Herring List-Id: devicetree@vger.kernel.org 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.hauer@pengutronix.de (Sascha Hauer) Date: Tue, 31 Mar 2015 19:52:34 +0200 Subject: [PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller In-Reply-To: <1427802658.32196.8.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> Message-ID: <20150331175234.GK9742@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |