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 A34C8CFD355 for ; Mon, 24 Nov 2025 21:19:12 +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: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:References: List-Owner; bh=tdjPnIM6TqpD1FiYWypJzBxdXFMlqjNcIoj6euKiUXg=; b=i+CEggsXwtjUdI /K/FRsC5PLFx+NtfUfAHQX4y/0fXVM8ZKN/11XArTplWAqhVJ0Oo/IBCx61dSFLtphx+nDJ/FG1D9 GvcInsS7OtjzOztIisks8zZxeMFpkOZvaVxBFdzOdp4MDgltAE3ai4iJFaIOI9Q0W2Lp4LVfJv2k2 7VwSz5qecxV53UX3kq3y4IPvieV72DhelbjMxy29RCOi7lA2CgLq3z6RBTdgUA7f0/JBb1BJqsZfF cIYJfT2RO5n0o6iHfIdXKXeSmBU7XjRqIkaC2v3zpd3kFx+vbbFvrUUwvHkPH+lOd+LjoNc5gFkuv mjF/CMAi1MrmEFDKDiFQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vNdxj-0000000CKUn-2kV6; Mon, 24 Nov 2025 21:19:07 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vNdxi-0000000CKUb-12IS; Mon, 24 Nov 2025 21:19:06 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 1FAC46016B; Mon, 24 Nov 2025 21:19:05 +0000 (UTC) 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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, 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