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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED 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 BED12C6786F for ; Thu, 1 Nov 2018 14:32:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EFA02082E for ; Thu, 1 Nov 2018 14:32:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7EFA02082E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-mips.org 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 S1728609AbeKAXfS (ORCPT ); Thu, 1 Nov 2018 19:35:18 -0400 Received: from eddie.linux-mips.org ([148.251.95.138]:40306 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728122AbeKAXfS (ORCPT ); Thu, 1 Nov 2018 19:35:18 -0400 Received: (from localhost user: 'macro', uid#1010) by eddie.linux-mips.org with ESMTP id S23991034AbeKAOae1ajmS (ORCPT + 1 other); Thu, 1 Nov 2018 15:30:34 +0100 Date: Thu, 1 Nov 2018 14:30:34 +0000 (GMT) From: "Maciej W. Rozycki" To: Christoph Hellwig cc: Paul Burton , iommu@lists.linux-foundation.org, Marek Szyprowski , Robin Murphy , Greg Kroah-Hartman , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] MIPS: Fix `dma_alloc_coherent' returning a non-coherent allocation In-Reply-To: <20181101083346.GA7136@lst.de> Message-ID: References: <20180914095808.22202-1-hch@lst.de> <20180914095808.22202-5-hch@lst.de> <20181031203206.GA28337@lst.de> <20181101051359.GA4164@lst.de> <20181101083346.GA7136@lst.de> User-Agent: Alpine 2.21 (LFD 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 1 Nov 2018, Christoph Hellwig wrote: > Oops, yes this looks good: BTW, for anyone missing hardware suitable for serious DMA testing I can recommend getting a pair of DEFPA cards, the ubiquitous PCI version of this board, cheaply available, which is the same except for a different host bus bridge ASIC, developed later. They can be wired back to back similarly to Ethernet adapters (or in a loop if you have 2 or more dual attachment versions), no other hardware is required save for patch cords. Version 3 (DEFPA-xC) boards support universal PCI signalling, older ones are 5V-only. These devices are a stellar example of fine engineering[1]. Our `defxx' driver, which I believe has been adapted from the DEC OSF/1 one referred in the said document, has some latency and other issues that I plan to address sometime, once I have sorted higher-priority issues, however hardware itself is excellent. References: [1] Chran-Ham Chang et al., "High-performance TCP/IP and UDP/IP Networking in DEC OSF/1 for Alpha AXP", Digital Technical Journal, vol. 5, no. 1 (Winter 1993), "Network Adapter Characteristics", p. 7 Maciej