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=-0.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 783B7C43387 for ; Sat, 22 Dec 2018 18:05:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4A2BA20874 for ; Sat, 22 Dec 2018 18:05:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390598AbeLVSFh (ORCPT ); Sat, 22 Dec 2018 13:05:37 -0500 Received: from gate.crashing.org ([63.228.1.57]:56988 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731280AbeLVSFh (ORCPT ); Sat, 22 Dec 2018 13:05:37 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w9F2jR2g007872; Sun, 14 Oct 2018 21:45:28 -0500 Message-ID: Subject: Re: [PATCH 16/33] powerpc/powernv: remove dead npu-dma code From: Benjamin Herrenschmidt To: Alexey Kardashevskiy , Christoph Hellwig , Paul Mackerras , Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 15 Oct 2018 13:45:26 +1100 In-Reply-To: <7709932d-efb8-2c9b-5128-99cc491c302b@ozlabs.ru> References: <20181009132500.17643-1-hch@lst.de> <20181009132500.17643-17-hch@lst.de> <7709932d-efb8-2c9b-5128-99cc491c302b@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-1.fc28) 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 Mon, 2018-10-15 at 12:34 +1100, Alexey Kardashevskiy wrote: > On 10/10/2018 00:24, Christoph Hellwig wrote: > > This code has been unused since it was merged and is in the way of > > cleaning up the DMA code, thus remove it. > > > > This effectively reverts commit 5d2aa710 ("powerpc/powernv: Add support > > for Nvlink NPUs"). > > > This code is heavily used by the NVIDIA GPU driver. Some of it is, yes. And while I don't want to be involved in the discussion about that specific can of worms, there is code in this file related to the custom "always error" DMA ops that I suppose we could remove, which is what is getting in the way of Christoph cleanups. It's just meant as a debug stuff to catch incorrect attempts at doing the dma mappings on the wrong "side" of the GPU. Cheers, Ben.