Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752862AbcCVXiu (ORCPT ); Tue, 22 Mar 2016 19:38:50 -0400 Received: from mail-vk0-f51.google.com ([209.85.213.51]:33360 "EHLO mail-vk0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826AbcCVXis (ORCPT ); Tue, 22 Mar 2016 19:38:48 -0400 MIME-Version: 1.0 In-Reply-To: <56F1D33A.9050509@redhat.com> References: <1458686031-31031-1-git-send-email-moritz.fischer@ettus.com> <56F1CC7B.7040909@redhat.com> <56F1D33A.9050509@redhat.com> Date: Tue, 22 Mar 2016 16:38:47 -0700 Message-ID: Subject: Re: [RFC 0/2] staging: ion: of_ion_device_get From: Moritz Fischer To: Laura Abbott Cc: Arnd Bergmann , Greg KH , arve@android.com, riandrews@android.com, Sumit Semwal , dan.carpenter@oracle.com, sriram@marirs.net.in, Linux Kernel Mailing List , devel@driverdev.osuosl.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1439 Lines: 55 On Tue, Mar 22, 2016 at 4:20 PM, Laura Abbott wrote: > On 03/22/2016 04:08 PM, Moritz Fischer wrote: >> >> Hi Laura, >> >> On Tue, Mar 22, 2016 at 3:51 PM, Laura Abbott wrote: >> >>> In the past what drivers have done is a foo_ion_client_create which has >>> the >>> reference >>> to the ion_device created from ion_device_create. Drivers then call the >>> foo_ion_client_create function. >> >> >> Oh, so you mean you add a function to create a client to the platform >> device implementing >> the heap and the export this function? >> >> heap implements: >> >> foo_create_client(); >> >> driver calls: >> >> foo_create_client() ? >> > > Yes, exactly > >>> Can you elaborate more on your sharing and allocation flow? This might >>> suggest >>> another idea. >> >> >> Well I'll have a bunch of DMA streams to / from an FPGA that contains >> DMA engines & accelerators. To that end >> my userland software would allocate say 64 buffers, hand them over to >> driver A to queue/deque them. >> >> In future I might want to share these buffers between streams and with >> other peripherals on the same bus, >> which is why I looked at ION. >> > > If allocation is coming from userspace and drivers are only importing > you should be using the dma_buf APIs instead of Ion APIs directly. > Ion is a dma_buf exporter and dma_buf APIs are the preferred API. > >> Thanks, >> >> Moritz >> > > Thanks, > Laura