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 9A30E22424D; Thu, 17 Apr 2025 08:39:54 +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=1744879194; cv=none; b=KTEFcX7PiwN3Wd1vGHVPsnUiq6uVfEBjsSk0xSRb1rG7pUWOi42UJFGa6fk41tpp2EWyRzb4naaeKwA9sfLRW36l/iZge3dcdlIPV6yYI5xatsNJmpiqbw1ITCsTdeaNiZdT0xlGLe49CN0nkQERnUbtS58TRKK5eOGQlBalDP4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744879194; c=relaxed/simple; bh=E2pUwIa3M2j8+TwNI8zdHacoOXOQYH/elMF2JStWijg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pPJ4j5WLE5hXojK7It3DYer8VoU1kmP1FJthfAwEAfMkdtm1Vjdix5yMP3M7GCBAvwiXexvg7YKg0FoSQIPx1/AeaUP554obGjS60pDPDZ6ayF0iRlUpYY6UA/v9nMNvELeQ+fLSyKY0NmZ3tGVk8QW0zz+KvSWd7YO720BPiDA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fHW40nqI; 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="fHW40nqI" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <52a2f6dc-1e13-4473-80f2-989379df4e95@163.com> 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