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 A5FA3A41; Mon, 14 Jul 2025 19:32:16 +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=1752521537; cv=none; b=RAHzD3nIqw3zYjE3O3NyqX3yURnCTJV82IXShyAqMuAq5V/wHKFebxnvVc/RzcHb53BenPJgBTKGY5FN0rtYC8rXO/A5bys6gpKxwWMFwS2UyKi7a9jFjSjKAYxwsj7TmF/7ki4AJqxZo7Hp5XnPkV32NE5oCllmvtKIPNW1drs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752521537; c=relaxed/simple; bh=AQrxO9GMuQ9aYr3Jm8n6Ii4kIOHde1vJf8LTBljYPok=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=iWNGRSS9IY9mrscsR3ySmIY7wTV+nt0+e5NrBnyrKZZGRJJptZYTYHfBpyrIM7hvCElclGRAkxN8HIgJhycyypInLQ8p4vwJLqCtknb0ugoe1NZMbGItUcShvmtUr3UDd8pK77LHVx+ymzmtwxosThtvNYsyaAm9/sR6nHrkh0E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kt2Y25vt; 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="kt2Y25vt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 199CBC4CEED; Mon, 14 Jul 2025 19:32:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752521536; bh=AQrxO9GMuQ9aYr3Jm8n6Ii4kIOHde1vJf8LTBljYPok=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=kt2Y25vtysozivPuujqnU8y4JyYjsGSn7HGHKaj5Wh8im8SJ1Xp4AhW8AGo2lP1+5 zQEGTF+WevtHwlWsbyhKSwTxlET+cZv73pqoC8/5HHIVTIQ0twq6Iovw3U2pz4ue5j r8L0vuloLaWvG/U1xJ3+3sALLbE6AZNV6/R/aByiqKxQEYiDjLiGmQTMyxiaD2bPe3 StjJOwSesK0gl0/B6TchmYHyagJ3VaUupNEVzqDfUZi8oDQe9ueKnLO4kpq221zmpT ptb5CayJ9iFz5OOBWHkbyYDrRZBjKpBGeRRsEDSCQFAN6fN40wGIzb7/Gh4DPuThtc mkMIBPsaLSQUQ== Date: Mon, 14 Jul 2025 14:32:14 -0500 From: Bjorn Helgaas To: Hans Zhang <18255117159@163.com> Cc: Manivannan Sadhasivam , Ilpo =?utf-8?B?SsOkcnZpbmVu?= , Krishna Chaitanya Chundru , Bjorn Helgaas , Jingoo Han , Lorenzo Pieralisi , Rob Herring , Jeff Johnson , Bartosz Golaszewski , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , linux-pci@vger.kernel.org, LKML , linux-arm-msm@vger.kernel.org, mhi@lists.linux.dev, linux-wireless@vger.kernel.org, ath11k@lists.infradead.org, qiang.yu@oss.qualcomm.com, quic_vbadigan@quicinc.com, quic_vpernami@quicinc.com, quic_mrana@quicinc.com, Jeff Johnson Subject: Re: [PATCH v4 06/11] PCI/ASPM: Clear aspm_disable as part of __pci_enable_link_state() Message-ID: <20250714193214.GA2415073@bhelgaas> Precedence: bulk X-Mailing-List: linux-arm-msm@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: <470742a6-861e-498e-9da4-1fa213969c7e@163.com> On Sun, Jul 13, 2025 at 12:05:18AM +0800, Hans Zhang wrote: > On 2025/7/12 17:35, Manivannan Sadhasivam wrote: > ... > > > IMO the "someday" goal should be that we get rid of aspm_policy > > > and enable all the available power saving states by default. We > > > have sysfs knobs that administrators can use if necessary, and > > > drivers or quirks can disable states if they need to work around > > > hardware defects. > > > > Yeah, I think the default should be powersave and let the users > > disable it for performance if they want. > > Perhaps I don't think so. At present, our company's testing team has > tested quite a few NVMe SSDS. As far as I can remember, the SSDS > from two companies have encountered problems and will hang directly > when turned on. We have set CONFIG_PCIEASPM_POWERSAVE=y by default. > When encountering SSDS from these two companies, we had to add > "pcie_aspm.policy=default" in the cmdline, and then the boot worked > normally. Currently, we do not have a PCIe protocol analyzer to > analyze such issues. The current approach is to modify the cmdline. > So I can't prove whether it's a problem with the Root Port of our > SOC or the SSD device. Have you reported these? > Here I agree with Bjorn's statement that sometimes the EP is not > necessarily very standard and there are no hardware issues. > Personally, I think the default is default or performance. When > users need to save power, they should then decide whether to > configure it as powersave or powersupersave. Sometimes, if the EP > device connected by the customer is perfect, they can turn it on to > save power. But if the EP is not perfect, at least they will > immediately know what caused the problem. We should discover device defects as early as possible so we can add quirks for them. Defaulting to ASPM being partly disabled means it gets much less testing and users end up passing around "fixes" like booting with "pcie_aspm.policy=default" or similar. I do not want users to trip over a device that doesn't work and have to look for workarounds on the web. I also think it's somewhat irresponsible of us to consume more power than necessary. But as Mani said, this would be a big change and might have to be done with a BIOS date check or something to try to avoid regressions. Bjorn