Received: by 2002:ad5:474a:0:0:0:0:0 with SMTP id i10csp5598210imu; Sat, 1 Dec 2018 22:14:00 -0800 (PST) X-Google-Smtp-Source: AFSGD/Vx8ToYuk8ohJRF5yn4bc2BiBmf4iDoDS6G6wnP9DXsxpS7YbyOVGVonTns8DrNk/eDmGv9 X-Received: by 2002:a62:1709:: with SMTP id 9mr11291479pfx.249.1543731240501; Sat, 01 Dec 2018 22:14:00 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1543731240; cv=none; d=google.com; s=arc-20160816; b=UcM7M7DU2t4R96M44BCx0oKtl6dEI4YOaulL1lghW1uJdKb6cMX+IM7Mtw2iY1Vedx jMokz7hKKoJR/pKKEV3uN4fYxNt9BNZEDqxGptxMeP1j+KlmsUaUmwB9SwkFGBHq6ryJ Ltk9BtYA4wQEjtMyN00q8LEie/+rRjEFfsR3Oia1sMVkMtJ2rqSOW+dFKbRKBEbr44/2 TdsdutbcbVceluZjUlFvuVy0B4FnCA3I2USuv2Rfs90MKEPwTkbxIhqPqZC+IXYBblf6 VhkYxYqFbq8Ed1blIJyc5l2ocNhQEvz54+tHvv9+h9P1a0Osd0SGUfjsj0P2t1G+IwDn b1jQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:date:cc:to:from:subject :message-id; bh=PdqKlQb245+C/sXgMEWy2iBu/WDYd7OLxK0rh6dskF4=; b=QImki5vD7cvPJZDUEePnfbQqn9c5Jeq9nBT3wK00Xlm7gR44WqaPpWpipVX1TI2sji GNVE7mC1vPpJP5RNxPMhLs4ipcWFx7fADuZKqT6RZfJVXEm0lM38iQUjJ/Zc/GmQ6jtI +nWUNOBpRTOIZ3vghRlTJK1XPeWI61pmZ3CAFN+CIbwU14vCw1IJOPSRhxA2Jr91wuyQ DOk9xvF1yBWiEVC3FDZ6O2pFmIyX0Fp/bXm5kNjrIjxXgRJFIDy9G64HTFgwnue8LHG5 cXYlZWkUlC7+1ZzYLu+t17iIrqED0ongqsk8PGY2ICMRe+XtcSAIboyiz5OJIQtWB6sK nuVw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id u9si12060229plk.61.2018.12.01.22.13.13; Sat, 01 Dec 2018 22:14:00 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725554AbeLBGL0 (ORCPT + 99 others); Sun, 2 Dec 2018 01:11:26 -0500 Received: from gate.crashing.org ([63.228.1.57]:47746 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725355AbeLBGL0 (ORCPT ); Sun, 2 Dec 2018 01:11:26 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id wB26B3sd012208; Sun, 2 Dec 2018 00:11:04 -0600 Message-ID: <42b1408cafe77ebac1b1ad909db237fe34e4d177.camel@kernel.crashing.org> Subject: Re: use generic DMA mapping code in powerpc V4 From: Benjamin Herrenschmidt To: Rui Salvaterra , hch@lst.de Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Sun, 02 Dec 2018 17:11:02 +1100 In-Reply-To: References: <20181130103222.GA23393@lst.de> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.2 (3.30.2-2.fc29) 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 Fri, 2018-11-30 at 11:44 +0000, Rui Salvaterra wrote: > Thanks for the quick response! I applied it on top of your > powerpc-dma.4 branch and retested. > I'm not seeing nouveau complaining anymore (I'm not using X11 or any > DE, though). > In any case and FWIW, this series is > > Tested-by: Rui Salvaterra Talking of which ... Christoph, not sure if we can do something about this at the DMA API level or keep hacks but some adapters such as the nVidia GPUs have a HW hack we can use to work around their limitations in that case. They have a register that can program a fixed value for the top bits that they don't support. This works fine for any linear mapping with an offset, provided they can program the offset in that register and they have enough DMA range to cover all memory from that offset. I can probably get the info about this from them so we can exploit it in nouveau. Cheers, Ben. > Thanks, > Rui