From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2EC391865ED; Wed, 16 Oct 2024 19:38:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729107484; cv=none; b=BynfS8jrGog4bMOYW6iUdyZsRw7wnVLVqng8TNJEVzeUWnsQxP0tJ6bd1syZQPKmdLL1rPq5lPpfyYOobhwypbw+vB4W6Kh54gPrB1AIFr4SxHsM1sysZKKj88R1C2U3ZpjjK4yLvyXU5wnB121B2SIsZ6LUdOqOuO7SEGml8zc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729107484; c=relaxed/simple; bh=6dGoC9a9JiCAYeGpX5fIjP+CJ42IJn9E3kkE2FQNvL0=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=inyC2DyD2OqWYWJwvWc79ldVxQagOBNy0UedOPPAfAqMuODEyTx8JxXuJ4ckoVJppuCCseYOp1RHHENPdvPzNwL3GiISppkTNUM3UyrXahDeryp5unO4To/1UHpFdha7O59m+kiKGTkygWNeYGQ1h/pvcd0Weuk0tOEbAWKx8Oc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tS1OkGaV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tS1OkGaV" 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> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: 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