From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752048AbaCFNzb (ORCPT ); Thu, 6 Mar 2014 08:55:31 -0500 Received: from mail-bl2lp0203.outbound.protection.outlook.com ([207.46.163.203]:20702 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751055AbaCFNz3 (ORCPT ); Thu, 6 Mar 2014 08:55:29 -0500 From: Yao Yuan To: Marek Vasut CC: "wsa@the-dreams.de" , "mark.rutland@arm.com" , "shawn.guo@linaro.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-i2c@vger.kernel.org" Subject: =?big5?B?tarOYDogW1BBVENIIHYyIDEvMl0gaTJjOiBhZGQgRE1BIHN1cHBvcnQgZm9yIGZy?= =?big5?Q?eescale_i2c_driver?= Thread-Topic: [PATCH v2 1/2] i2c: add DMA support for freescale i2c driver Thread-Index: AQHPOEj6II9jTAb8MUaErre9ZA32b5rTWhmAgAALnECAABZdgIAAALzwgAB5LgCAAB4vQg== Date: Thu, 6 Mar 2014 13:55:09 +0000 Message-ID: References: <1394002352-8380-1-git-send-email-yao.yuan@freescale.com> <201403060541.21665.marex@denx.de> <50e0997786a0459eb08c9d92813253f9@BL2PR03MB338.namprd03.prod.outlook.com>,<201403061257.42755.marex@denx.de> In-Reply-To: <201403061257.42755.marex@denx.de> Accept-Language: zh-CN, en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [125.39.108.73] x-forefront-prvs: 0142F22657 x-forefront-antispam-report: SFV:NSPM;SFS:(10009001)(6009001)(428001)(377454003)(24454002)(189002)(199002)(51704005)(69226001)(79102001)(54356001)(74366001)(87936001)(53806001)(224303002)(92566001)(95416001)(2656002)(51856001)(33646001)(76482001)(90146001)(83072002)(56816005)(74876001)(85852003)(97336001)(77982001)(81542001)(59766001)(95666003)(63696002)(46102001)(81342001)(76576001)(76796001)(93136001)(83322001)(80976001)(4396001)(19580395003)(19580405001)(74502001)(74662001)(31966008)(81816001)(66066001)(87266001)(81686001)(50986001)(93516002)(47976001)(76786001)(47446002)(94946001)(80022001)(85306002)(20776003)(97186001)(47736001)(56776001)(86362001)(54316002)(74706001)(94316002)(74316001)(49866001)(65816001)(24736002);DIR:OUT;SFP:1101;SCL:1;SRVR:BL2PR03MB337;H:BL2PR03MB338.namprd03.prod.outlook.com;FPR:FABEDCEE.FD90A571.B7CDBBCC.73E2A0B2.20130;MLV:sfv;PTR:InfoNoRecords;MX:1;A:1;LANG:en; Content-Type: text/plain; charset="big5" MIME-Version: 1.0 X-OriginatorOrg: freescale.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id s26Dtd6U025892 On Thursday, March 06, 2014 at 09:46:03 PM, Marek Vasut wrote: >On Thursday, March 06, 2014 at 06:02:03 AM, Yao Yuan wrote: > > On Thu, March 06, 2014 at 12:44:14 PM, Marek Vasut wrote: > > > On Thursday, March 06, 2014 at 05:36:14 AM, Yao Yuan wrote: > > > > On Thu, March 06, 2014 at 11:23:50 AM, Marek Vasut wrote: > > > > > On Wednesday, March 05, 2014 at 07:52:31 AM, Yuan Yao wrote: > > > > > > Add dma support for i2c. This function depend on DMA driver. > > > > > > You can turn on it by write both the dmas and dma-name properties > > > > > > in dts node. > > > > > > > > > > > > Signed-off-by: Yuan Yao > > > > > > --- > > > > > > > > > > [...] > > > > > > > > > > > @@ -601,6 +826,7 @@ static int i2c_imx_probe(struct > > > > > > platform_device > > > > > > > > > > *pdev) > > > > > > > > > > > void __iomem *base; > > > > > > int irq, ret; > > > > > > u32 bitrate; > > > > > > > > > > > >+ u32 phy_addr; > > > > > > > > > > > > dev_dbg(&pdev->dev, "<%s>\n", __func__); > > > > > > > > > > > > @@ -611,6 +837,7 @@ static int i2c_imx_probe(struct > > > > > > platform_device > > > > > > > > > > *pdev) > > > > > > > > > > > } > > > > > > > > > > > > res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > > > > > > > + phy_addr = res->start; > > > > > > > > > > Uh ... Shawn, I really think I am lost here. Don't you need to map > > > > > this memory before you can use it for DMA ? The DMA mapping function > > > > > should give you the physical address and is the right way to go > > > > > about this instead of pulling the address from here, no ? > > > > > > > > > > I might be wrong here, I am rather uncertain, so please help me out. > > > > > Thanks! > > > > > > > > Hi, Marek, Thanks for your suggestion. > > > > Here you can review the code in include/linux/ioport.h The > > > > resource->start describes the entity on the CPU bus as a starting > > > > physical address. So I thinks it can used for dma directly. > > > > > > This doesn't feel right for some reason. If this is a register area, you > > > should > > > ioremap() it. If it's a memory area you do DMA to/from, you need to make > > > sure you correctly flush/invalidate caches and properly handle the > > > effects the write buffer might have. But I have a feeling you actually do > > > DMA to/from register space here ? > > > > Yes, It's a register area. But I don't know why I should ioremap() it? It's > > a bus address and DMA can use it directly. Is there some problem for my > > understanding ? > > I am not too sure here, thus I am poking someone who can clearly answer this. OK, and thank you for pointing out many ugly code in my patch. It's very useful for me. {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I