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 E423323F431; Mon, 24 Nov 2025 21:19:04 +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=1764019145; cv=none; b=jQ8AnonSLvoMVJ8J8w/ebQYEqQijjU6+n9Mp8LF0ZuA0nnHjLDaZt0HwKzWOjdFCjRH8NoEGHvQZDwedF4tgt3AybvW/Uj7Edso1YqfiP1j9TSAPIxbcvvn2p3dfV93CKs9rzB5PYDPvytX88V0SCMrG9MlbmgzPPt1l8xfq090= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764019145; c=relaxed/simple; bh=DiDxFX94NXXIUzvxcS2+Fvuf/2KCTsklF/QbVLxONjU=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=lTDRHIGIRwszk4ZaeKCzsg29wfoGyrXK2SolszGMqCy/JbpLp05LOiGFOnjkm7plTZJaPo98ohoET27gLHID95mNfqyJV9psyZF2cKn7HiyuPhpk2ms30Yi4Bz7/yg/1PDQynGsFIz9pT7/wx74GdrtxUs/7D0TNj6DGMIvzOdw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DNAG9tPd; 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="DNAG9tPd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9DA9AC4CEFB; Mon, 24 Nov 2025 21:19:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764019144; bh=DiDxFX94NXXIUzvxcS2+Fvuf/2KCTsklF/QbVLxONjU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=DNAG9tPd/4nqTFtv4FYVdApqANdOMIrVWr3lJDe2sCqX42/Zeq4glUcUMsPhjiD+Q t2m7XFOTFBJhBOnUXsp47g2HExxgWWc/M14S26V+yUlO67lCX508xmAuCm2EQWMZw2 A9g6zO4z1WS9mllO+NiBHFuu7ogogLgoi+xlWZDuE4PeOTvPRBLrlW+QIX+D4AnHiu ExwSSAnfYbD2Et6LgjBwH1OESwSoyPlL+5t+B8e6G+n+xmDrNVq0ILqfngMEvVR86r a9TEkRX0ihIQi0Sja/eRtaJCbzbtDFER07VnFSBlrlpyMt1OtS6hK1uMjACv6wF2FN 5QMXNSJwunAtg== Date: Mon, 24 Nov 2025 15:19:03 -0600 From: Bjorn Helgaas To: Manivannan Sadhasivam Cc: Niklas Cassel , Shawn Lin , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Rob Herring , Heiko Stuebner , Kever Yang , Simon Xue , Damien Le Moal , Dragan Simic , FUKAUMI Naoki , Diederik de Haas , Richard Zhu , Frank Li , Lucas Stach , Shawn Guo , Sascha Hauer , Fabio Estevam , Conor Dooley , Krzysztof Kozlowski , Thierry Reding , Jonathan Hunter , Hans Zhang , linux-tegra@vger.kernel.org, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, kernel@pengutronix.de, Bjorn Helgaas Subject: Re: [PATCH v2 1/4] PCI: dwc: Advertise L1 PM Substates only if driver requests it Message-ID: <20251124211903.GA2712341@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@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: On Thu, Nov 20, 2025 at 01:10:56PM +0530, Manivannan Sadhasivam wrote: > On Tue, Nov 18, 2025 at 03:42:15PM -0600, Bjorn Helgaas wrote: > > From: Bjorn Helgaas > > > > L1 PM Substates require the CLKREQ# signal and may also require > > device-specific support. If CLKREQ# is not supported or driver support is > > lacking, enabling L1.1 or L1.2 may cause errors when accessing devices, > > e.g., > > > > nvme nvme0: controller is down; will reset: CSTS=0xffffffff, PCI_STATUS=0x10 > > > > If the kernel is built with CONFIG_PCIEASPM_POWER_SUPERSAVE=y or users > > enable L1.x via sysfs, users may trip over these errors even if L1 > > Substates haven't been enabled by firmware or the driver. > > > > To prevent such errors, disable advertising the L1 PM Substates unless the > > driver sets "dw_pcie.l1ss_support" to indicate that it knows CLKREQ# is > > present and any device-specific configuration has been done. > > Going by this reasoning, why can't we enable L1 PM Substates for > these platforms by default? I think we can, in a separate series. I don't have time to deal with this before the v6.19 merge window, but you can certainly do that. Bjorn