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=-4.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_ALL,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 0CA5BC433E2 for ; Mon, 14 Sep 2020 14:25:57 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 B3624208DB for ; Mon, 14 Sep 2020 14:25:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="YmbqZ4gx"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="iTb1X2eP" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3624208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: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=0phrHYgEONVrdFk74bttPQ9GyVRWm0isfrXY3bAqBew=; b=YmbqZ4gxmvm/RG2/4f+bSfoTH zeYUwH8elEUudGVrxoBKDvx6Flda+VP2jCrnthDUvTZbbCp0gRGx7HIW+aU2TmEq+Bz9l7ioWcEoD fiPusyGG70+uG7gZN/xnUctJwXnQTL420fi5Y0ItGwuDaLs1+vdDg5zWLOH37o+cNBkx+wBNQR6nC 84lH8Ag+GeYfwOtCnQmuQsgNARmldeJ+2x42PrZj/XyYxcDFfpkWhBK2UbFwzYAFDf2Fglw6nMXcg mH6Z1uCJHF3CsZuUNomISmibAfhTTDjDkICMOkbhJMCWtZc/JSK+JoX1DVgY3sT6MmTyk2TSwlOpf C3GqyA6oQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHpPH-0000Yo-T6; Mon, 14 Sep 2020 14:24:35 +0000 Received: from smtp-fw-9101.amazon.com ([207.171.184.25]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHpPE-0000Xm-Ld for linux-arm-kernel@lists.infradead.org; Mon, 14 Sep 2020 14:24:33 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1600093473; x=1631629473; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=IT81N7TrAfwYmLVOGjn/uSAZG0vmUEVcGJxsly/zgK8=; b=iTb1X2eP93LNenbMKe7+FAC5JBMRY6KTbWzvfj0XlRqMfsRcwqj9ChSy 8VG4QGiBrgxxxHuq2yAMvGQ4PbqZcuLDD5zgyzk0Gtjj5eGpAl02826Te tNZgMVluBua5zJuIItnedJBEGjK/uIUqDI85uZ33QyspFNyH52erJsOVM s=; X-IronPort-AV: E=Sophos;i="5.76,426,1592870400"; d="scan'208";a="67827301" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-1e-27fb8269.us-east-1.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9101.sea19.amazon.com with ESMTP; 14 Sep 2020 14:24:09 +0000 Received: from EX13MTAUEA002.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan2.iad.amazon.com [10.40.163.34]) by email-inbound-relay-1e-27fb8269.us-east-1.amazon.com (Postfix) with ESMTPS id E3B72A0660; Mon, 14 Sep 2020 14:24:07 +0000 (UTC) Received: from EX13D37UEA003.ant.amazon.com (10.43.61.137) by EX13MTAUEA002.ant.amazon.com (10.43.61.77) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 14 Sep 2020 14:24:07 +0000 Received: from EX13MTAUEA002.ant.amazon.com (10.43.61.77) by EX13D37UEA003.ant.amazon.com (10.43.61.137) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 14 Sep 2020 14:24:07 +0000 Received: from dev-dsk-csbisa-2a-37939146.us-west-2.amazon.com (172.19.34.216) by mail-relay.amazon.com (10.43.61.169) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 14 Sep 2020 14:24:07 +0000 Received: by dev-dsk-csbisa-2a-37939146.us-west-2.amazon.com (Postfix, from userid 800212) id 20C52193; Mon, 14 Sep 2020 14:24:06 +0000 (UTC) Date: Mon, 14 Sep 2020 14:24:06 +0000 From: Clint Sbisa To: Jason Gunthorpe Subject: Re: [PATCH] arm64: Enable PCI write-combine resources under sysfs Message-ID: <20200914142406.k44zrnp2wdsandsp@amazon.com> References: <28d333afc73bd854390f8c39691a735040ba5b39.camel@kernel.crashing.org> <20200910094600.GA22840@e121166-lin.cambridge.arm.com> <20200910123758.GC904879@nvidia.com> <20200910151721.GA25809@e121166-lin.cambridge.arm.com> <20200910171033.GG904879@nvidia.com> <44acc22377958a57c738f5139c5b5df2841c2544.camel@kernel.crashing.org> <20200910232938.GJ904879@nvidia.com> <3110e00a1f4df7b7359ba4f2b7f86a35aa47405e.camel@kernel.crashing.org> <20200911214225.hml2wbbq2rofn4re@amazon.com> <20200914141726.GA904879@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200914141726.GA904879@nvidia.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200914_102432_829590_5255B3DD X-CRM114-Status: GOOD ( 16.39 ) 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: Lorenzo Pieralisi , catalin.marinas@arm.com, Leon Romanovsky , Benjamin Herrenschmidt , Bjorn Helgaas , linux-pci@vger.kernel.org, will@kernel.org, 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+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Sep 14, 2020 at 11:17:26AM -0300, Jason Gunthorpe wrote: > On Fri, Sep 11, 2020 at 09:42:25PM +0000, Clint Sbisa wrote: > > > There's no DMA involved with this BAR-- the driver writes a portion of the > > packet contents in addition to the descriptors, which generally increases the > > number of TLPs if write-combine isn't used. Furthermore, this BAR is only used > > for writes and never for reads. > > You use DPDK without DMA? How does receive work? That was not worded well. DMA is used, but the first X bytes of the packet are written directly to this BAR instead of being DMA'd-- the rest of the data is DMA'd. > > > As Jason noted in the other reply to this email, the Linux ENA driver makes use > > of WC by using devm_ioremap_wc(). > > As Ben noted we don't have kernel accessors to make this portable or > safe :( And therein lies our dilemma... Clint _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel