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 80EEAC369B2 for ; Thu, 17 Apr 2025 08:42:01 +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-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=qm3e2vl0D67OULbMQ9hRKDjA0GFGhhzN4QyTNiBFMV8=; b=VhaUvpQrVL7xKE0sjC8osDy6U+ bAmL+4N7Mt5WBTGrZ5pdY/343xm4Yo04bcyRbWCT4Fh0a0ht7+dZBwcrlFrnUKEspgUf/heGC3m+c 7ctTHG4qPz+tbAA4XVwmIi37z60om0lBttL5PK63AVUYq14DFu9XFT8Rl/v92X1K82NMqBSTHfhFa gZ/LH+gdXTIyAGNqT/MSW4JqKXY6Xx4HUPsSE1jJK81cF8CI+kJeIeicNs3L6uOucb37nbK6L9Wpl 15pWdmAWcKdr8Uoaeyic56sn0XLD+SptObAXqOk8s8bYbFhTsnGF6rsrwnUyjvx43NdDmpDQHgtbX qlTJSByg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u5Kof-0000000CIq2-3MTF; Thu, 17 Apr 2025 08:41:49 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u5Kmp-0000000CIXS-0ouO; Thu, 17 Apr 2025 08:39:56 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 7008A5C480F; Thu, 17 Apr 2025 08:37:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79DD9C4CEE4; Thu, 17 Apr 2025 08:39:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744879194; bh=E2pUwIa3M2j8+TwNI8zdHacoOXOQYH/elMF2JStWijg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fHW40nqIuGIijzpwiC5akHwMbGFOSJ1+jL/+ZngNMd+K4bT8s12plZRNkkJxe3Ye2 T8B6niULHBTtrEf6UmCUUM9/KWJyOZWnA/XdG7sNqBRJ8hbHfaWeoh+XiQ/vjjhlYm rcXjSzZOhJ4M69YByAp+kWgKcOYvTxrXM987mgY5aldRHWUfVwHQRX5W/JVNON68vW zxTzKQBI6cJGk9lvviHSrZuaAOoOLckcMA0zHmuqnS1jJxNrMWvODO86eQYnvmmcqN n79/wMFaQsyb2BOlxWf8PPRZGH/6e2Kn9L7QppLIT6z7DEuM3T23odCLaNxggvv/8b akXryhkCD7z7w== Date: Thu, 17 Apr 2025 10:39:49 +0200 From: Niklas Cassel To: Hans Zhang <18255117159@163.com> Cc: Shawn Lin , lpieralisi@kernel.org, kw@linux.com, bhelgaas@google.com, heiko@sntech.de, manivannan.sadhasivam@linaro.org, robh@kernel.org, jingoohan1@gmail.com, thomas.richard@bootlin.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Subject: Re: [PATCH] PCI: dw-rockchip: Configure max payload size on host init Message-ID: References: <20250416151926.140202-1-18255117159@163.com> <85643fe4-c7df-4d64-e852-60b66892470a@rock-chips.com> <52a2f6dc-1e13-4473-80f2-989379df4e95@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52a2f6dc-1e13-4473-80f2-989379df4e95@163.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250417_013955_273732_A2680379 X-CRM114-Status: GOOD ( 14.36 ) 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, Apr 17, 2025 at 04:07:51PM +0800, Hans Zhang wrote: > On 2025/4/17 15:48, Niklas Cassel wrote: > > Hi Niklas and Shawn, > > Thank you very much for your discussion and reply. > > I tested it on RK3588 and our platform. By setting pci=pcie_bus_safe, the > maximum MPS will be automatically matched in the end. > > So is my patch no longer needed? For RK3588, does the customer have to > configure CONFIG_PCIE_BUS_SAFE or pci=pcie_bus_safe? > > Also, for pci-meson.c, can the meson_set_max_payload be deleted? I think the only reason why this works is because pcie_bus_configure_settings(), in the case of pcie_bus_config == PCIE_BUS_SAFE, will walk the bus and set MPS in the bridge to the lowest of the downstream devices: https://github.com/torvalds/linux/blob/v6.15-rc2/drivers/pci/probe.c#L2994-L2999 So Hans, if you look at lspci for the other RCs/bridges that don't have any downstream devices connected, do they also show DevCtl.MPS 256B or do they still show 128B ? One could argue that for all policies (execept for maybe PCIE_BUS_TUNE_OFF), pcie_bus_configure_settings() should start off by initializing DevCtl.MPS to DevCap.MPS (for the bridge itself), and after that pcie_bus_configure_settings() can override it depending on policy, e.g. set MPS to 128B in case of pcie_bus_config == PCIE_BUS_PEER2PEER, or walk the bus in case of pcie_bus_config == PCIE_BUS_SAFE. That way, we should be able to remove the setting for pci-meson.c as well. Bjorn, thoughts? Kind regards, Niklas