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 1387CD2FFEF for ; Fri, 18 Oct 2024 23:32:47 +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=pbthLOh220fKYdT1oLywVRMo4Ti5PzXPwYkvrrpJoH4=; b=p0teV81OlTadmG44CJ5WsRAwLU R5/i0vBgORRZx23s9neaqPBHekA2k2N9kOxXalfsDyoIFUxY0BecbpVj+BFXqZ3mKEQpgEPZA1v+0 RtbWwKXEa8Zty0kL+0PGmBle0wHpZ4QZJE5yBb2N+QoD/Pk3fsLNR5y6acoGMrRhM2oJ8kfpfIfHp hwR2vJp6Z78ueSqqaKG42eJ/svulyDZkX8cd9KNOEkX6995lsWx0hNtbLjEYkeUnc7Kz5mcGOqEO1 qgCLW6jPslqCxUONeruO4KmYWvqw2f9unQ1jT1KDD+m3pJS0hPgQCFxtCcloJHLJacpIT8MsgaE6W FWjpQGCg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t1wSR-00000002GUs-2JF8; Fri, 18 Oct 2024 23:32:35 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t1wQy-00000002GNA-24eW; Fri, 18 Oct 2024 23:31:05 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 5F3385C0FD2; Fri, 18 Oct 2024 23:30:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3CFBDC4CEC3; Fri, 18 Oct 2024 23:31:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729294263; bh=0c1uwez6hOT+dNwlWPtjBKASFttyCohhN5DW6r850zU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=PQoZSC5ZpMUk0IexHBKuJKJsUwLGwE2NWMA146OlcwDNQbQz1Hv3eCrovdbGDq2UC X3GCddARrNgFrc3t+A6q3keB9WcR3fC2dd9EBUe4HTg7iXeVwD740AkklLzmpe8+LC km6yj/Ey4vyBNuEUDHN1pRm/w713wzPPoGXXCIvDnSOlHnboOnhoGgkCvfRh+HPAAA LAkY5U+XfEr8MBLnqYp2fviSHdAPiZdvJHyvP/kEG2xpY3YD/1fDtcD5DuHmrEw1Oq NaKuB0kbTYVB50670og89LCvR6eRohIpjgdw+uEXXq0dN6lNJ8SL+14Fuv4j+sZuYM RI1tEIB9XCsIw== Date: Fri, 18 Oct 2024 18:31:01 -0500 From: Bjorn Helgaas To: Stanimir Varbanov Cc: Jim Quinlan , Florian Fainelli , 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: <20241018233101.GA769193@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <27c18374-8120-40bd-87d2-183c40945fbf@suse.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20241018_163104_644906_C1D53CE9 X-CRM114-Status: GOOD ( 23.67 ) 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 Thu, Oct 17, 2024 at 11:02:33AM +0300, Stanimir Varbanov wrote: > On 10/16/24 22:38, Bjorn Helgaas wrote: > > 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? > > Existing SoCs will not be impacted. It could be theoretically possible > to break inbound window translations only if you wrongly populate window > sizes in DT. I guess this is the part that I missed -- the inbound window sizes come from DT (via bridge->dma_ranges, IIUC), and the patch merely supports encoding of larger windows than previously. Bjorn