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 A5A1E1CDFBD; Tue, 12 Nov 2024 23:44:34 +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=1731455075; cv=none; b=aTsm2NaxsvgaEg2tcyXVX2nRoCgg+ATFOvDLdAtrCSxXWko6+35ZFJolbMgTM21U/eb/FYxCMyc1FSAeVy6QIEt1oF/uYeDys8WXFa02sDwyRZxRtwqE/kiFdwXDzRqiQlnILNPW51ginM9MeNd57i6rQFkGUIXNDa168t/9rrI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731455075; c=relaxed/simple; bh=UZCb9fS+hhkL+JEKJ9NO1EcmESMvQfEetmouChM+sds=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=f7H4I7srXgyvwFrx0/tmaE/qJJ3MVvGDCwadehbJrveS0DyBE8YzQZv1i5bw9h7w+Mn3PstyTELI8VQcWbLFlBw3sgRDApTbsXHykvKDDfkg1iF0D0wfp1NxfrPv7KWEC+LP87LcLzpPkviT8fKDoKcVUJKyYQBa4I92T6JWVYk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=o1ZNhDxJ; 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="o1ZNhDxJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FAE1C4CECD; Tue, 12 Nov 2024 23:44:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731455074; bh=UZCb9fS+hhkL+JEKJ9NO1EcmESMvQfEetmouChM+sds=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=o1ZNhDxJXEmxRM8biQl6+CgCrq0SZXFtzfdxz6TZkf6DVzK1ukp5fpuifm5toup8b A2fO0wjA28nsV0jV7mH5RUEe/pDgETnDXQQVQ2NB6rLrsVwHJn1kkZ5pHIuDZqOHms XLYoPAZNHy6ZKdvT06cBA8P9BCFGco/QnYJ6wQ87AVWpZA0UrC9JfUxnzEr/pHJnt0 gUFbQz9RWPrGG1Dev0o81RunTyRk5zABaSP8+YCVI+0N+BmNw9RKaKQj4SXVE2EOLC Wl9z2e2H2UkWPGlbcaV9jLpsIMT/+XK1w6XgkunBCEHxSGv9qsHauSdhnX+jRsGVoZ NFzImbUJit/VQ== Date: Tue, 12 Nov 2024 17:44:32 -0600 From: Bjorn Helgaas To: Krishna chaitanya chundru Cc: Kevin Xie , Lorenzo Pieralisi , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Manivannan Sadhasivam , Rob Herring , Bjorn Helgaas , Markus.Elfring@web.de, quic_mrana@quicinc.com, rafael@kernel.org, m.szyprowski@samsung.com, linux-pm@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 0/2] PCI: Enable runtime pm of the host bridge Message-ID: <20241112234432.GA1868852@bhelgaas> Precedence: bulk X-Mailing-List: linux-pm@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: <20241111-runtime_pm-v7-0-9c164eefcd87@quicinc.com> On Mon, Nov 11, 2024 at 02:11:51PM +0530, Krishna chaitanya chundru wrote: > It is a property of the runtime PM framework that it can only > follow continuous dependency chains. That is, if there is a device > with runtime PM disabled in a dependency chain, runtime PM cannot be > enabled for devices below it and above it in that chain both at the > same time. > > Since runtime PM is disabled for host bridge, the state of the child > devices under the host bridge is not taken into account by PM framework > for the top level parent, PCIe controller. So PM framework, allows > the controller driver to enter runtime PM irrespective of the state > of the devices under the host bridge. > > So enable runtime pm of the host bridge device, so that dependency > chain in maintained between endpoint devices and the controller driver. > > PM framework expectes parent runtime pm enabled before enabling runtime > pm of the child. As PCIe starfive device is enabling runtime pm after > the pci_host_probe which enables runtime pm of the child device i.e for > the bridge device a warning is shown saying "pcie-starfive 940000000.pcie: > Enabling runtime PM for inactive device with active children" and also > shows possible circular locking dependency detected message. > > As it is must to enable parent device's runtime PM before enabling child's > runtime pm as the pcie-starfive device runtime pm is enabled after child > runtime starfive device is seeing the warning. > > In the first patch fix the pcie-starfive driver by enabling runtime > pm before calling pci_host_probe(). > > All other PCIe controller drivers are enabling runtime pm before > calling pci_host_probe() which is as expected so don't require any > fix like pcie-starfive driver. > > Signed-off-by: Krishna chaitanya chundru Provisionally applied to pci/pm for v6.13. I see a typo or two, so the commit logs will likely be updated, but I pushed the branch to get build testing started. > --- > Changes in v7: > - Bring the cover letter details to commit message as suggested by bjorn. > - Add a comment in the driver to ensure pm_runtime_enable is called > before host bridge pm_runtime_enable(). > - Link to v6: https://lore.kernel.org/r/20241017-runtime_pm-v6-0-55eab5c2c940@quicinc.com > Changes in v6: > - include the patch by mayank which fixes runtime pm enable order for > pcie starfive driver. > Changes in v5: > - call pm_runtime_no_callbacks() as suggested by Rafael. > - include the commit texts as suggested by Rafael. > - Link to v4: https://lore.kernel.org/linux-pci/20240708-runtime_pm-v4-1-c02a3663243b@quicinc.com/ > Changes in v4: > - Changed pm_runtime_enable() to devm_pm_runtime_enable() (suggested by mayank) > - Link to v3: https://lore.kernel.org/lkml/20240609-runtime_pm-v3-1-3d0460b49d60@quicinc.com/ > Changes in v3: > - Moved the runtime API call's from the dwc driver to PCI framework > as it is applicable for all (suggested by mani) > - Updated the commit message. > - Link to v2: https://lore.kernel.org/all/20240305-runtime_pm_enable-v2-1-a849b74091d1@quicinc.com > Changes in v2: > - Updated commit message as suggested by mani. > - Link to v1: https://lore.kernel.org/r/20240219-runtime_pm_enable-v1-1-d39660310504@quicinc.com > > --- > Krishna chaitanya chundru (1): > PCI: Enable runtime pm of the host bridge > > Mayank Rana (1): > PCI: starfive: Enable PCIe controller's runtime PM before probing host bridge > > drivers/pci/controller/plda/pcie-starfive.c | 10 +++++++--- > drivers/pci/probe.c | 11 +++++++++++ > 2 files changed, 18 insertions(+), 3 deletions(-) > --- > base-commit: 2f87d0916ce0d2925cedbc9e8f5d6291ba2ac7b2 > change-id: 20241016-runtime_pm-d3dbf41736b6 > > Best regards, > -- > Krishna chaitanya chundru >