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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 38F41D2A556 for ; Wed, 16 Oct 2024 19:44:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To: Content-Transfer-Encoding:Content-Type:MIME-Version: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:References:List-Owner; bh=4yS0qCoVZEBKtiFX219hdiTNnNJ+ooudWsizBe1W85Q=; b=XMmHYlvhh0LLRxifDh9mGjDwGf dCskOyfzckI0/8z/lnUYTwhUfpne7s3r/p+8jd3ula/xKRKzdRz2b0o7q4ZkedAFPjV26wRP1uRo4 94VseivYqesnXkpvzvbhziGoOngl4YT5ycrSrkxuxWgGNaP0EsczvqqsNnzxy1kK+cY8oLNo5BALa apldpGyRHW7PdrdOFiY0/biKuBN6yvXddCqeBaqqFWZFvx57WKy0UeIP2z2KLvhHpaN9MkFIdTGhY POX4JhGv2e4i00dfBTVBx122z2W7fuEoWdo9VNAJwv1CsXJXvm4F5It7CDe1Rc0iyCfBRbNGm4J16 Ouq+BQvA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t19wD-0000000CqVL-0fUx; Wed, 16 Oct 2024 19:44:05 +0000 Received: from nyc.source.kernel.org ([147.75.193.91]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t19qQ-0000000CpVU-0TVS; Wed, 16 Oct 2024 19:38:07 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 151DFA41FE4; Wed, 16 Oct 2024 19:37:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 82649C4CEC5; Wed, 16 Oct 2024 19:38:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729107483; bh=6dGoC9a9JiCAYeGpX5fIjP+CJ42IJn9E3kkE2FQNvL0=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=tS1OkGaVsIsv4ZJFraTecKZ2QFO4nUAEAoichSykLSfGjHXeNTJSjpqnrQ69xbYnh URdczNK3W+SkrSWC/V9ZyJFc9etIglHTD7o4KNBZIdKvzjqj500kca4FrMAUoIE5vT yok6MdDEoiwPwiCpUm9r8k+S3Fb9BSAzaEwWEl8vupOe9Nhlb6Eztq4LBhL2hGIOg/ 5z4dLaBohTguxawa/FZHPqiMK3SiTDXcrO2aMgFmprS2/knK5C7rT2wSNrVQxz0VQz PQxGoNWWyxGOQ3DZKevs1L3byjSr1qq1p3uI1zEn1PwLP8fZu5X0Y2cNMIHCmerxLr 5NgHJdKtbl58A== Date: Wed, 16 Oct 2024 14:38:02 -0500 From: Bjorn Helgaas To: Jim Quinlan Cc: Florian Fainelli , Stanimir Varbanov , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, linux-pci@vger.kernel.org, Broadcom internal kernel review list , Thomas Gleixner , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Nicolas Saenz Julienne , Bjorn Helgaas , Lorenzo Pieralisi , kw@linux.com, Philipp Zabel , Andrea della Porta , Phil Elwell , Jonathan Bell Subject: Re: [PATCH v3 04/11] PCI: brcmstb: Expand inbound size calculation helper Message-ID: <20241016193802.GA645895@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241016_123806_241782_7419A40F X-CRM114-Status: GOOD ( 24.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 16, 2024 at 01:09:00PM -0400, Jim Quinlan wrote: > On Mon, Oct 14, 2024 at 1:25 PM Bjorn Helgaas wrote: > > On Mon, Oct 14, 2024 at 10:10:11AM -0700, Florian Fainelli wrote: > > > On 10/14/24 09:57, Bjorn Helgaas wrote: > > > > On Mon, Oct 14, 2024 at 04:07:03PM +0300, Stanimir Varbanov wrote: > > > > > BCM2712 memory map can supports up to 64GB of system > > > > > memory, thus expand the inbound size calculation in > > > > > helper function up to 64GB. > > > > > > > > The fact that the calculation is done in a helper isn't important > > > > here. Can you make the subject line say something about supporting > > > > DMA for up to 64GB of system memory? > > > > > > > > This is being done specifically for BCM2712, but I assume it's safe > > > > for *all* brcmstb devices, right? > > > > > > It is safe in the sense that all brcmstb devices with this PCIe > > > controller will adopt the same encoding of the size, all of the > > > currently supported brcmstb devices have a variety of > > > limitations when it comes to the amount of addressable DRAM > > > however. Typically we have a hard limit at 4GB of DRAM per > > > memory controller, some devices can do 2GB x3, 4GB x2, or 4GB > > > x1. > > > > > > Does that answer your question? > > > > I'd like something in the commit log to the effect that while > > we're doing this to support more system memory on BCM2712, this > > change is safe for other SoCs that don't support as much system > > memory. > > This setting configures the size of an RC's inbound window to system > memory. Any inbound access outside of all of the inbound windows > will be discarded. > > Some existing SoCs cannot support the 64GB size. Configuring such > an SoC to 64GB will effectively disable the entire window. So I *think* you're saying that this patch will break existing SoCs that don't support the 64GB size, right? Bjorn