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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 B0D9CC282DD for ; Fri, 10 Jan 2020 14:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EFA720721 for ; Fri, 10 Jan 2020 14:13:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728183AbgAJONJ (ORCPT ); Fri, 10 Jan 2020 09:13:09 -0500 Received: from foss.arm.com ([217.140.110.172]:45160 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727951AbgAJONJ (ORCPT ); Fri, 10 Jan 2020 09:13:09 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E075B328; Fri, 10 Jan 2020 06:13:08 -0800 (PST) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B292E3F534; Fri, 10 Jan 2020 06:13:07 -0800 (PST) Date: Fri, 10 Jan 2020 14:13:03 +0000 From: Andre Przywara To: Andrew Lunn Cc: "David S . Miller" , Radhey Shyam Pandey , Michal Simek , Robert Hancock , netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 12/14] net: axienet: Autodetect 64-bit DMA capability Message-ID: <20200110141303.2e5863ab@donnerap.cambridge.arm.com> In-Reply-To: <20200110140852.GF19739@lunn.ch> References: <20200110115415.75683-1-andre.przywara@arm.com> <20200110115415.75683-13-andre.przywara@arm.com> <20200110140852.GF19739@lunn.ch> Organization: ARM X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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, 10 Jan 2020 15:08:52 +0100 Andrew Lunn wrote: Hi Andrew, thanks for having a look! > > To autodetect this configuration, at probe time we write all 1's to such > > an MSB register, and see if any bits stick. > > So there is no register you can read containing the IP version? There is, and I actually read this before doing this check. But the 64-bit DMA capability is optional even in this revision. It depends on what you give it as the address width. If you say 32, the IP config tool disables the 64-bit capability completely, so it stays compatible with older revisions. Anything beyond 32 will enable the MSB register and will also require you to write to them. Cheers, Andre 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 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 CBAA9C33CA3 for ; Fri, 10 Jan 2020 14:13:13 +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 9EEB220721 for ; Fri, 10 Jan 2020 14:13:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="UOBQKyIw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9EEB220721 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=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.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject: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=P2oE6EWAkS6s93EPgVmK9ulPoMtu5jK8Zgg6qac/USg=; b=UOBQKyIwhsx2nb VwNoEQUx7Dmz6jOoWdmP41nYT8/LNny2WFdiqtv6HEXjgUmF9/X8naDXiDIfrOQRDXz/TX2msxfya 9hR6oTHvKEZrHrhk0EZJ7YrwXe0tYetd0HN5zS4TO+SUQX5ASgRLULS7gfP6qRb4xt/BB3xqrWz47 cPn7WkwhOAt2XNXPHhuN4TGqqzTB4LQAm+G1Z+IalvRnWurw8cJxGOWX4nqxjiFcxgQzHBNXNazI7 ZglmDX/ADyucJeIf59N3DvnsQJ6xEsolh9XiIY32jdIWQTNf5ppVuDwBBMEQ7Az5cCv+a1b8ynJT7 dk20KA8JSjBA5DANwrrw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipv2H-0000mt-3U; Fri, 10 Jan 2020 14:13:13 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipv2D-0000mA-Kd for linux-arm-kernel@lists.infradead.org; Fri, 10 Jan 2020 14:13:10 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E075B328; Fri, 10 Jan 2020 06:13:08 -0800 (PST) Received: from donnerap.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B292E3F534; Fri, 10 Jan 2020 06:13:07 -0800 (PST) Date: Fri, 10 Jan 2020 14:13:03 +0000 From: Andre Przywara To: Andrew Lunn Subject: Re: [PATCH 12/14] net: axienet: Autodetect 64-bit DMA capability Message-ID: <20200110141303.2e5863ab@donnerap.cambridge.arm.com> In-Reply-To: <20200110140852.GF19739@lunn.ch> References: <20200110115415.75683-1-andre.przywara@arm.com> <20200110115415.75683-13-andre.przywara@arm.com> <20200110140852.GF19739@lunn.ch> Organization: ARM X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; aarch64-unknown-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200110_061309_720760_7BBAA57B X-CRM114-Status: GOOD ( 10.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: netdev@vger.kernel.org, Radhey Shyam Pandey , Michal Simek , linux-kernel@vger.kernel.org, Robert Hancock , "David S . Miller" , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 10 Jan 2020 15:08:52 +0100 Andrew Lunn wrote: Hi Andrew, thanks for having a look! > > To autodetect this configuration, at probe time we write all 1's to such > > an MSB register, and see if any bits stick. > > So there is no register you can read containing the IP version? There is, and I actually read this before doing this check. But the 64-bit DMA capability is optional even in this revision. It depends on what you give it as the address width. If you say 32, the IP config tool disables the 64-bit capability completely, so it stays compatible with older revisions. Anything beyond 32 will enable the MSB register and will also require you to write to them. Cheers, Andre _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel