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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 735CCC4360F for ; Wed, 3 Apr 2019 18:16:03 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id BEBBC20700 for ; Wed, 3 Apr 2019 18:16:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEBBC20700 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44ZDm014jGzDqJ5 for ; Thu, 4 Apr 2019 05:16:00 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=newverein.lst.de; envelope-from=hch@lst.de; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de X-Greylist: delayed 338 seconds by postgrey-1.36 at bilbo; Thu, 04 Apr 2019 05:14:22 AEDT Received: from newverein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44ZDk65NKfzDqGJ for ; Thu, 4 Apr 2019 05:14:22 +1100 (AEDT) Received: by newverein.lst.de (Postfix, from userid 2407) id EC48268AFE; Wed, 3 Apr 2019 20:08:28 +0200 (CEST) Date: Wed, 3 Apr 2019 20:08:28 +0200 From: Christoph Hellwig To: Oded Gabbay Subject: Re: Question about Power8/9, PHB3/4 and setting of DMA mask Message-ID: <20190403180828.GC28682@lst.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, Christoph Hellwig Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Sun, Mar 31, 2019 at 12:50:21PM +0300, Oded Gabbay wrote: > Due to some limitation in Goya, the driver first need to allocate a > 2MB chunk in a DMA-able address under 39 bits and then we would like > to move to using up to 48 bits. Therefore, the driver first tries to > set the DMA mask to 39 bits, allocate the 2MB area and later on, > change the DMA mask to 48 bits. On x86 this works fine. You can't just change the DMA mask while you have active allocations, this will fail for many implementations.