From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752214AbeERON6 (ORCPT ); Fri, 18 May 2018 10:13:58 -0400 Received: from smtprelay6.synopsys.com ([198.182.37.59]:57870 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbeERONy (ORCPT ); Fri, 18 May 2018 10:13:54 -0400 From: Alexey Brodkin To: "hch@lst.de" CC: "deanbo422@gmail.com" , "linux-kernel@vger.kernel.org" , "linux-sh@vger.kernel.org" , "nios2-dev@lists.rocketboards.org" , "linux-xtensa@linux-xtensa.org" , "linux-m68k@lists.linux-m68k.org" , "linux-alpha@vger.kernel.org" , "linux-hexagon@vger.kernel.org" , "linux-snps-arc@lists.infradead.org" , "iommu@lists.linux-foundation.org" , "green.hu@gmail.com" , "openrisc@lists.librecores.org" , "linux-arm-kernel@lists.infradead.org" , "monstr@monstr.eu" , "linux-parisc@vger.kernel.org" , "linux-c6x-dev@linux-c6x.org" , "linux-arch@vger.kernel.org" , "sparclinux@vger.kernel.org" Subject: Re: [PATCH 02/20] dma-mapping: provide a generic dma-noncoherent implementation Thread-Topic: [PATCH 02/20] dma-mapping: provide a generic dma-noncoherent implementation Thread-Index: AQHT7rJwE0RiyYL8c0WIr1H3arr2Xg== Date: Fri, 18 May 2018 14:13:47 +0000 Message-ID: <913e288c5aabf0224cedcf2eb0c9be309745eace.camel@synopsys.com> References: <20180511075945.16548-1-hch@lst.de> <20180511075945.16548-3-hch@lst.de> <20180518132731.GA31125@lst.de> In-Reply-To: <20180518132731.GA31125@lst.de> Accept-Language: en-US, ru-RU Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.121.8.87] Content-Type: text/plain; charset="utf-8" Content-ID: MIME-Version: 1.0 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 w4IEE4do025531 Hi Christoph, On Fri, 2018-05-18 at 15:27 +0200, hch@lst.de wrote: > On Fri, May 18, 2018 at 01:03:46PM +0000, Alexey Brodkin wrote: > > Note mmc_get_dma_dir() is just "data->flags & MMC_DATA_WRITE ? DMA_TO_DEVICE : DMA_FROM_DEVICE". > > I.e. if we're preparing for sending data dma_noncoherent_map_sg() will have DMA_TO_DEVICE which > > is quite OK for passing to dma_noncoherent_sync_sg_for_device() but in case of reading we'll have > > DMA_FROM_DEVICE which we'll pass to dma_noncoherent_sync_sg_for_device() in dma_noncoherent_map_sg(). > > > > I'd say this is not entirely correct because IMHO arch_sync_dma_for_cpu() is supposed to only be used > > in case of DMA_FROM_DEVICE and arch_sync_dma_for_device() only in case of DMA_TO_DEVICE. > > arc overrides the dir paramter of the dma_sync_single_for_device/ > dma_sync_single_for_cpu calls. My patches dropped that, and I have > restored that, and audit for the other architectures is pending. Well at least for me that's a confusion what is a reason to pass direction to function which purpose is already known. I'd say that XXX_sync_for_device() doesn't need _variable_ direction as an argument, otherwise what does that mean if we pass DMA_FROM_DEVICE to that function? > That being said the existing arc code still looks rather odd as it > didn't do the same thing for the scatterlist versions of the calls. That might easily be the case so good we caught that now and it will be fixed :) > I've thrown in a few patches into my new tree to make the sg versions > make the normal calls, and to clean up the area a bit. I'll try your newer series now, thanks! -Alexey