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_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 9136AECE58C for ; Mon, 7 Oct 2019 12:07:33 +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 640F720867 for ; Mon, 7 Oct 2019 12:07:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="MMIy2P4n" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 640F720867 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-nvme-bounces+linux-nvme=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: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=vg7LkBYwnBf8zcWomBUBuCGU7x/3rJiUHnXMaEpZg6w=; b=MMIy2P4nyAiTd5 3uyoUsc0pVbF0wZQTTHM7GdoWKpgitDt7nMJNfoyhbkffmgf0QXGNXBgubH3wo9dBD91oOXEN24Lo epBRzzRWnK1QlMvwMBTDPVd6hwdP5wU23/q5xCoqZDqJGqN7LI7x1q3bxgMGRmCpMlSi7/ojiz++D sjOtWvA2mg+kjhuDKVi6Rn97cuLSNhLu1+2E2DXTQ/1eR1ar3k72FxPMH/zUsVAMwINLoVO6Smd45 EcltPCfexQYKmy0op9NZ1PwNmmxY1SuqwI8usTym+zIarcNJy7F7QQAElYlMF7z8RTjfJqTUE2esj eEXK1CWw79Xh6AdMYXRw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iHRnW-0004hu-VJ; Mon, 07 Oct 2019 12:07:30 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92.2 #3 (Red Hat Linux)) id 1iHRnU-0004de-Ao for linux-nvme@lists.infradead.org; Mon, 07 Oct 2019 12:07:30 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 43C3F68B20; Mon, 7 Oct 2019 14:07:21 +0200 (CEST) Date: Mon, 7 Oct 2019 14:07:21 +0200 From: Christoph Hellwig To: Ard Biesheuvel Subject: Re: [PATCH v3] nvme: retain split access workaround for capability reads Message-ID: <20191007120721.GA21060@lst.de> References: <20191007114253.30735-1-ard.biesheuvel@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191007114253.30735-1-ard.biesheuvel@linaro.org> 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-20191007_050728_513413_8C88B211 X-CRM114-Status: GOOD ( 10.11 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sagi@grimberg.me, ilias.apalodimas@linaro.org, linux-nvme@lists.infradead.org, axboe@fb.com, kbusch@kernel.org, hch@lst.de Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Oct 07, 2019 at 01:42:53PM +0200, Ard Biesheuvel wrote: > This fixes a boot issue on some ARM boxes with NVMe behind a Synopsys > DesignWare PCIe host controller. > static int nvme_pci_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val) > { > - *val = readq(to_nvme_dev(ctrl)->bar + off); > + /* use a split read to work around buggy interconnects */ > + *val = lo_hi_readq(to_nvme_dev(ctrl)->bar + off); I though this was to fix back up the broken Apple controllers? If you interconnect doesn't support 8-byte MMIO read/write TLPs you have a much deeper problem, as this will break all drivers using readq/writeq. And we currently only have compile time detection for readq/writeq, not runtime so you'll have to invent a scheme if this works at all or not. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme