From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754892Ab3JBRPe (ORCPT ); Wed, 2 Oct 2013 13:15:34 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:15219 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754164Ab3JBRPc (ORCPT ); Wed, 2 Oct 2013 13:15:32 -0400 X-IronPort-AV: E=Sophos;i="4.90,1019,1371081600"; d="scan'208";a="57044804" Date: Wed, 2 Oct 2013 18:14:47 +0100 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: Catalin Marinas CC: Stefano Stabellini , Konrad Rzeszutek Wilk , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "Ian.Campbell@citrix.com" Subject: Re: [PATCH v6 10/19] xen: introduce xen_alloc/free_coherent_pages In-Reply-To: <20131002170747.GG29794@arm.com> Message-ID: References: <1380298207-29151-10-git-send-email-stefano.stabellini@eu.citrix.com> <20130930153143.GQ3106@phenom.dumpdata.com> <20131002170747.GG29794@arm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2 Oct 2013, Catalin Marinas wrote: > On Wed, Oct 02, 2013 at 06:03:46PM +0100, Stefano Stabellini wrote: > > On Tue, 1 Oct 2013, Catalin Marinas wrote: > > > On 30 Sep 2013, at 16:31, Konrad Rzeszutek Wilk wrote: > > > > On Fri, Sep 27, 2013 at 05:09:58PM +0100, Stefano Stabellini wrote: > > > >> xen_swiotlb_alloc_coherent needs to allocate a coherent buffer for cpu > > > >> and devices. On native x86 and ARMv8 is sufficient to call > > > >> __get_free_pages in order to get a coherent buffer, while on ARM we need > > > >> to call the native dma_ops->alloc implementation. > > > >> > > > >> When arm64 stops using the swiotlb by default and starts having multiple > > > >> dma_ops implementations, we'll use __get_dma_ops there too. > > > > > > > > I presume this is a future TODO, not some further patch (in which > > > > case you should say in here the title of it). If it is a TODO could > > > > you stick that in the sentence here somewhere to make it crytal clear that > > > > it is not implemented. > > > > > > Thanks for pointing this out. The arm64 patch shouldn't be different > > > from arm here. I thought a subsequent patch already added > > > __get_dma_ops() for arm64. > > > > Yes, the arm64 patch already added __get_dma_ops. > > > > However I am not using __get_dma_ops to implement > > xen_alloc_coherent_pages for arm64 because I can just use > > __get_free_pages for the moment: > > So why do the work twice when we'll get coherency maintenance in the DMA > ops? Yeah, good point. From mboxrd@z Thu Jan 1 00:00:00 1970 From: stefano.stabellini@eu.citrix.com (Stefano Stabellini) Date: Wed, 2 Oct 2013 18:14:47 +0100 Subject: [PATCH v6 10/19] xen: introduce xen_alloc/free_coherent_pages In-Reply-To: <20131002170747.GG29794@arm.com> References: <1380298207-29151-10-git-send-email-stefano.stabellini@eu.citrix.com> <20130930153143.GQ3106@phenom.dumpdata.com> <20131002170747.GG29794@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 2 Oct 2013, Catalin Marinas wrote: > On Wed, Oct 02, 2013 at 06:03:46PM +0100, Stefano Stabellini wrote: > > On Tue, 1 Oct 2013, Catalin Marinas wrote: > > > On 30 Sep 2013, at 16:31, Konrad Rzeszutek Wilk wrote: > > > > On Fri, Sep 27, 2013 at 05:09:58PM +0100, Stefano Stabellini wrote: > > > >> xen_swiotlb_alloc_coherent needs to allocate a coherent buffer for cpu > > > >> and devices. On native x86 and ARMv8 is sufficient to call > > > >> __get_free_pages in order to get a coherent buffer, while on ARM we need > > > >> to call the native dma_ops->alloc implementation. > > > >> > > > >> When arm64 stops using the swiotlb by default and starts having multiple > > > >> dma_ops implementations, we'll use __get_dma_ops there too. > > > > > > > > I presume this is a future TODO, not some further patch (in which > > > > case you should say in here the title of it). If it is a TODO could > > > > you stick that in the sentence here somewhere to make it crytal clear that > > > > it is not implemented. > > > > > > Thanks for pointing this out. The arm64 patch shouldn't be different > > > from arm here. I thought a subsequent patch already added > > > __get_dma_ops() for arm64. > > > > Yes, the arm64 patch already added __get_dma_ops. > > > > However I am not using __get_dma_ops to implement > > xen_alloc_coherent_pages for arm64 because I can just use > > __get_free_pages for the moment: > > So why do the work twice when we'll get coherency maintenance in the DMA > ops? Yeah, good point. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH v6 10/19] xen: introduce xen_alloc/free_coherent_pages Date: Wed, 2 Oct 2013 18:14:47 +0100 Message-ID: References: <1380298207-29151-10-git-send-email-stefano.stabellini@eu.citrix.com> <20130930153143.GQ3106@phenom.dumpdata.com> <20131002170747.GG29794@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Return-path: In-Reply-To: <20131002170747.GG29794@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Catalin Marinas Cc: Stefano Stabellini , Konrad Rzeszutek Wilk , "xen-devel@lists.xensource.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "Ian.Campbell@citrix.com" List-Id: xen-devel@lists.xenproject.org On Wed, 2 Oct 2013, Catalin Marinas wrote: > On Wed, Oct 02, 2013 at 06:03:46PM +0100, Stefano Stabellini wrote: > > On Tue, 1 Oct 2013, Catalin Marinas wrote: > > > On 30 Sep 2013, at 16:31, Konrad Rzeszutek Wilk wrote: > > > > On Fri, Sep 27, 2013 at 05:09:58PM +0100, Stefano Stabellini wrote: > > > >> xen_swiotlb_alloc_coherent needs to allocate a coherent buffer for cpu > > > >> and devices. On native x86 and ARMv8 is sufficient to call > > > >> __get_free_pages in order to get a coherent buffer, while on ARM we need > > > >> to call the native dma_ops->alloc implementation. > > > >> > > > >> When arm64 stops using the swiotlb by default and starts having multiple > > > >> dma_ops implementations, we'll use __get_dma_ops there too. > > > > > > > > I presume this is a future TODO, not some further patch (in which > > > > case you should say in here the title of it). If it is a TODO could > > > > you stick that in the sentence here somewhere to make it crytal clear that > > > > it is not implemented. > > > > > > Thanks for pointing this out. The arm64 patch shouldn't be different > > > from arm here. I thought a subsequent patch already added > > > __get_dma_ops() for arm64. > > > > Yes, the arm64 patch already added __get_dma_ops. > > > > However I am not using __get_dma_ops to implement > > xen_alloc_coherent_pages for arm64 because I can just use > > __get_free_pages for the moment: > > So why do the work twice when we'll get coherency maintenance in the DMA > ops? Yeah, good point.