From mboxrd@z Thu Jan 1 00:00:00 1970 From: "hch@lst.de" Subject: Re: [PATCH v2 2/4] ARC: allow to use IOC and non-IOC DMA devices simultaneously Date: Thu, 23 Aug 2018 16:05:25 +0200 Message-ID: <20180823140525.GA26121@lst.de> References: <20180730162636.3556-1-Eugeniy.Paltsev@synopsys.com> <20180730162636.3556-3-Eugeniy.Paltsev@synopsys.com> <1534180089.3962.68.camel@synopsys.com> <81ddd506-1f7e-db82-4c77-ff08b1c15dd3@synopsys.com> <1534963226.3962.215.camel@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1534963226.3962.215.camel@synopsys.com> Sender: linux-kernel-owner@vger.kernel.org To: Eugeniy Paltsev Cc: Vineet Gupta , "linux-snps-arc@lists.infradead.org" , "hch@lst.de" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "Alexey.Brodkin@synopsys.com" List-Id: linux-arch.vger.kernel.org Btw, given that I assume this is 4.20 material now, any chance we could merge it through the dma-mapping tree? I have some major changes pending that would clash if done in a different tree, so I'd rather get it all together. > We check this flag in arch_dma_alloc (which are used in non-coherent case) to > skip MMU mapping if we are advertised that consistency is not required. > > So, actually we can get rid of this flag checking in arch_dma_alloc and > simply always do MMU mapping to enforce non-cachability and return > non-cacheable memory even if DMA_ATTR_NON_CONSISTENT is passed. > But I don't sure we want to do that. I plan to kill this flag for 4.20 (or 4.20 at latest) in favor of a better interface. But your implementation looks ok, so I'm fine with keeping it for now. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from verein.lst.de ([213.95.11.211]:54842 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730065AbeHWRdX (ORCPT ); Thu, 23 Aug 2018 13:33:23 -0400 Date: Thu, 23 Aug 2018 16:05:25 +0200 From: "hch@lst.de" Subject: Re: [PATCH v2 2/4] ARC: allow to use IOC and non-IOC DMA devices simultaneously Message-ID: <20180823140525.GA26121@lst.de> References: <20180730162636.3556-1-Eugeniy.Paltsev@synopsys.com> <20180730162636.3556-3-Eugeniy.Paltsev@synopsys.com> <1534180089.3962.68.camel@synopsys.com> <81ddd506-1f7e-db82-4c77-ff08b1c15dd3@synopsys.com> <1534963226.3962.215.camel@synopsys.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1534963226.3962.215.camel@synopsys.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Eugeniy Paltsev Cc: Vineet Gupta , "linux-snps-arc@lists.infradead.org" , "hch@lst.de" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" , "Alexey.Brodkin@synopsys.com" Message-ID: <20180823140525._0tKb_60NfkG95t2bPQiONXTDeDUP3dlv6w8TsjkJK4@z> Btw, given that I assume this is 4.20 material now, any chance we could merge it through the dma-mapping tree? I have some major changes pending that would clash if done in a different tree, so I'd rather get it all together. > We check this flag in arch_dma_alloc (which are used in non-coherent case) to > skip MMU mapping if we are advertised that consistency is not required. > > So, actually we can get rid of this flag checking in arch_dma_alloc and > simply always do MMU mapping to enforce non-cachability and return > non-cacheable memory even if DMA_ATTR_NON_CONSISTENT is passed. > But I don't sure we want to do that. I plan to kill this flag for 4.20 (or 4.20 at latest) in favor of a better interface. But your implementation looks ok, so I'm fine with keeping it for now.