From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D79E3C433F4 for ; Thu, 30 Aug 2018 22:11:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7B9042082C for ; Thu, 30 Aug 2018 22:11:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7B9042082C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727249AbeHaCQF (ORCPT ); Thu, 30 Aug 2018 22:16:05 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:39636 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725836AbeHaCQF (ORCPT ); Thu, 30 Aug 2018 22:16:05 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: ezequiel) with ESMTPSA id 66B732762BC Message-ID: <4fc5107f93871599ead017af7ad50f22535a7683.camel@collabora.com> Subject: Re: [RFC 2/3] USB: core: Add non-coherent buffer allocation helpers From: Ezequiel Garcia To: Christoph Hellwig Cc: linux-media@vger.kernel.org, linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Laurent Pinchart , Tomasz Figa , "Matwey V . Kornilov" , Alan Stern , kernel@collabora.com, Keiichi Watanabe Date: Thu, 30 Aug 2018 19:11:35 -0300 In-Reply-To: <20180830175850.GA11521@infradead.org> References: <20180830172030.23344-1-ezequiel@collabora.com> <20180830172030.23344-3-ezequiel@collabora.com> <20180830175850.GA11521@infradead.org> Organization: Collabora Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.2-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2018-08-30 at 10:58 -0700, Christoph Hellwig wrote: > Please don't introduce new DMA_ATTR_NON_CONSISTENT users, it is > a rather horrible interface, and I plan to kill it off rather sooner > than later. I plan to post some patches for a better interface > that can reuse the normal dma_sync_single_* interfaces for ownership > transfers. I can happily include usb in that initial patch set based > on your work here if that helps. Please do. Until we have proper allocators that go thru the DMA API, drivers will have to kmalloc the USB transfer buffers, and have streaming mappings. Which in turns mean not using IOMMU or CMA. Regards, Eze