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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 6FABAC2BB9A for ; Mon, 14 Dec 2020 16:09:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30D4122583 for ; Mon, 14 Dec 2020 16:09:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2439392AbgLNQJi (ORCPT ); Mon, 14 Dec 2020 11:09:38 -0500 Received: from foss.arm.com ([217.140.110.172]:49502 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2439348AbgLNQJ2 (ORCPT ); Mon, 14 Dec 2020 11:09:28 -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 459D130E; Mon, 14 Dec 2020 08:08:38 -0800 (PST) Received: from e121166-lin.cambridge.arm.com (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 29A893F66B; Mon, 14 Dec 2020 08:08:37 -0800 (PST) Date: Mon, 14 Dec 2020 16:08:29 +0000 From: Lorenzo Pieralisi To: Marek Vasut Cc: linux-pci@vger.kernel.org, Bjorn Helgaas , Geert Uytterhoeven , Wolfram Sang , Yoshihiro Shimoda , linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH] PCI: rcar: Always allocate MSI addresses in 32bit space Message-ID: <20201214160829.GA3623@e121166-lin.cambridge.arm.com> References: <20201016120431.7062-1-marek.vasut@gmail.com> <20201210181133.GA3766@e121166-lin.cambridge.arm.com> <83135f6f-8a98-4537-0df5-91a06af07955@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <83135f6f-8a98-4537-0df5-91a06af07955@gmail.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org On Sat, Dec 12, 2020 at 08:13:54PM +0100, Marek Vasut wrote: > On 12/10/20 7:11 PM, Lorenzo Pieralisi wrote: > > [...] > > > > diff --git a/drivers/pci/controller/pcie-rcar-host.c b/drivers/pci/controller/pcie-rcar-host.c > > > index 1194d5f3341b..ac5c7d7573a6 100644 > > > --- a/drivers/pci/controller/pcie-rcar-host.c > > > +++ b/drivers/pci/controller/pcie-rcar-host.c > > > @@ -753,7 +753,7 @@ static int rcar_pcie_enable_msi(struct rcar_pcie_host *host) > > > } > > > /* setup MSI data target */ > > > - msi->pages = __get_free_pages(GFP_KERNEL, 0); > > > + msi->pages = __get_free_pages(GFP_KERNEL | GFP_DMA32, 0); > > > > This does not do what you want on !CONFIG_ZONE_DMA32 (ie arm LPAE). > > How come? I would expect GFP_DMA32 allocates a buffer below 4 GiB in any > case. For ARM LPAE allocation falls back to ZONE_NORMAL that happens to work because if there is memory > 4GB it ends up in ZONE_HIGHMEM, so this patch should still work on ARM LPAE too. Regardless, thoughts above the alternative approach (that saves you a page allocation) ? Lorenzo