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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 E7C03C4743C for ; Mon, 7 Jun 2021 06:51:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CBB94611ED for ; Mon, 7 Jun 2021 06:51:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230256AbhFGGxC (ORCPT ); Mon, 7 Jun 2021 02:53:02 -0400 Received: from verein.lst.de ([213.95.11.211]:44692 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229578AbhFGGxB (ORCPT ); Mon, 7 Jun 2021 02:53:01 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 2A62B67373; Mon, 7 Jun 2021 08:51:09 +0200 (CEST) Date: Mon, 7 Jun 2021 08:51:08 +0200 From: Christoph Hellwig To: Guo Ren Cc: Christoph Hellwig , Nick Kossifidis , Drew Fustini , Anup Patel , Palmer Dabbelt , wefu@redhat.com, Wei Wu =?utf-8?B?KOWQtOS8nyk=?= , linux-riscv , Linux Kernel Mailing List , linux-arch , linux-sunxi@lists.linux.dev, Guo Ren , Paul Walmsley , Benjamin Koch , Matteo Croce , Wei Fu Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Message-ID: <20210607065108.GA24872@lst.de> References: <20210519064435.GA3076809@x1> <20210519065352.GA31590@lst.de> <29733b0931d9dd6a2f0b6919067c7efe@mailhost.ics.forth.gr> <20210607062701.GB24060@lst.de> 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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 07, 2021 at 02:41:14PM +0800, Guo Ren wrote: > Double/Triple the size of physical memory regions can't be accepted by > SOC vendors, because it wastes HW resources. > Some cost-down soc interconnects only have 32bit~34bit width of > physical address, are you sure you could force them to expand it? (I > can't) > > > or somewhat dynamic. > How can HW implement with dynamic modifying PMA? What's the granularity? I'm just stating the requirements from the Linux DMA perspective. You also do not need tripple the address space, just double. 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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 136F7C47082 for ; Mon, 7 Jun 2021 06:51:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D7C6C611ED for ; Mon, 7 Jun 2021 06:51:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D7C6C611ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=1iwJIyNInEerkvqfzp3YoU16pJynSDwGa0a96UVGBAw=; b=fe+WkP/aXYfGis C3BwuI5w0Fm59zRZL4hJopnnex8aOqn4n1uO5y5WJ82xnKP6ej+1e4Pan8SHTuYHHr+vKTuu4V34G pw1OqL4bLagBkp4FD8++53xVKuDXhZl7gxC6Zyi+68czVWqMYeKi487JtpL+gvsHdQL9e/3cvLNmi Z9bCtzOdX9gl7YZquSPNgk6v1DH/Tcac3TiccP5h5bRrpX8y9zfI9BoJnnfDW5pICWmHu82kdLwKQ HDlWRdsLthIq/WL44pBpWtFDPju+JozVDoBcFRNsDCA3fDWfkykPCePVNWNIBhTBadxElqqZMiCXh vcxxGzC1Yx0J5NofMd5Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1lq96P-001ofA-ME; Mon, 07 Jun 2021 06:51:13 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1lq96N-001oe4-45 for linux-riscv@lists.infradead.org; Mon, 07 Jun 2021 06:51:12 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2A62B67373; Mon, 7 Jun 2021 08:51:09 +0200 (CEST) Date: Mon, 7 Jun 2021 08:51:08 +0200 From: Christoph Hellwig To: Guo Ren Cc: Christoph Hellwig , Nick Kossifidis , Drew Fustini , Anup Patel , Palmer Dabbelt , wefu@redhat.com, Wei Wu =?utf-8?B?KOWQtOS8nyk=?= , linux-riscv , Linux Kernel Mailing List , linux-arch , linux-sunxi@lists.linux.dev, Guo Ren , Paul Walmsley , Benjamin Koch , Matteo Croce , Wei Fu Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support Message-ID: <20210607065108.GA24872@lst.de> References: <20210519064435.GA3076809@x1> <20210519065352.GA31590@lst.de> <29733b0931d9dd6a2f0b6919067c7efe@mailhost.ics.forth.gr> <20210607062701.GB24060@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210606_235111_344052_3B4795D3 X-CRM114-Status: GOOD ( 12.29 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Mon, Jun 07, 2021 at 02:41:14PM +0800, Guo Ren wrote: > Double/Triple the size of physical memory regions can't be accepted by > SOC vendors, because it wastes HW resources. > Some cost-down soc interconnects only have 32bit~34bit width of > physical address, are you sure you could force them to expand it? (I > can't) > > > or somewhat dynamic. > How can HW implement with dynamic modifying PMA? What's the granularity? I'm just stating the requirements from the Linux DMA perspective. You also do not need tripple the address space, just double. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv