From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Wei Hu (Xavier)" Subject: Re: [PATCH for-next 2/4] RDMA/hns: Add IOMMU enable support in hip08 Date: Thu, 9 Nov 2017 09:30:08 +0800 Message-ID: <5A03AFA0.5090505@huawei.com> References: <1506763741-81429-1-git-send-email-xavier.huwei@huawei.com> <1506763741-81429-3-git-send-email-xavier.huwei@huawei.com> <20170930161023.GI2965@mtr-leonro.local> <59DF60A3.7080803@huawei.com> <5fe5f9b9-2c2b-ab3c-dafa-3e2add051bbb@arm.com> <59F97BBE.5070207@huawei.com> <5A011E49.6060407@huawei.com> <20171107154838.GC21466@ziepe.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20171107154838.GC21466-uk2M96/98Pc@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jason Gunthorpe Cc: Robin Murphy , Leon Romanovsky , shaobo.xu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, xavier.huwei-WVlzvzqoTvw@public.gmane.org, lijun_nudt-9Onoh4P/yGk@public.gmane.org, oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, charles.chenxin-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, linuxarm-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, liuyixian-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, zhangxiping3-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, shaoboxu-WVlzvzqoTvw@public.gmane.org List-Id: linux-rdma@vger.kernel.org On 2017/11/7 23:48, Jason Gunthorpe wrote: > On Tue, Nov 07, 2017 at 10:45:29AM +0800, Wei Hu (Xavier) wrote: > >> We reconstruct the code as below: >> It replaces dma_alloc_coherent with __get_free_pages and >> dma_map_single functions. So, we can vmap serveral ptrs returned by >> __get_free_pages, right? > Can't you just use vmalloc and dma_map that? Other drivers follow that > approach.. > > However, dma_alloc_coherent and dma_map_single are not the same > thing. You can't touch the vmap memory once you call dma_map unless > the driver also includes dma cache flushing calls in all the right > places. > > The difference is that alloc_coherent will return non-cachable memory > if necessary, while get_free_pages does not. > > Jason Hi, Jason Thanks for your suggestion. We will fix it. Regards Wei Hu > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html