From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout1.hostsharing.net (mailout1.hostsharing.net [83.223.95.204]) (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 EBD4D328B61; Fri, 17 Jul 2026 08:27:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=83.223.95.204 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784276824; cv=none; b=qSHnvfW6+vrhseZgUuPKvtKwgTJxgbj7MdOfQYHz2UcJIGFp125aA5phWDoWAxUnIYE2pC3V2cErxQKeAUKWqcLXS6GDtmAY/6cWBIYvXXzNUfkAI3WqXCT4sMUtFFnATRbWIXipuMyEP6I3LrrD/oxXSO864Ztr1QEFTY18y3I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784276824; c=relaxed/simple; bh=SZpvxKaGw+MkAMyQrY7eCnjAOu2pAQPjLqS2PNbJuqk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LEpSxP6UEQF3He4vQ8Vfn+KfL4PpeERofcEgB8IGNszhQ+KLoeTizJ0AWDb1KhS1Ewn+wcTSrJMDjjRmgjNyD2mNfQaCrfNSK5ji1IGnx1k29pXp1lkAd9Q3ByPEsR5cbhum2pebd2yRW5jCtVBdhClWPEeQKZ3qhUgG0NwIegc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de; spf=pass smtp.mailfrom=wunner.de; arc=none smtp.client-ip=83.223.95.204 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=wunner.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wunner.de Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384 client-signature ECDSA (secp384r1) client-digest SHA384) (Client CN "*.hostsharing.net", Issuer "GlobalSign GCC R6 AlphaSSL CA 2025" (verified OK)) by mailout1.hostsharing.net (Postfix) with ESMTPS id 47200372; Fri, 17 Jul 2026 10:26:53 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 2DFD8603E05C; Fri, 17 Jul 2026 10:26:53 +0200 (CEST) Date: Fri, 17 Jul 2026 10:26:53 +0200 From: Lukas Wunner To: Bjorn Helgaas Cc: Brian Norris , linux-kernel@vger.kernel.org, Manivannan Sadhasivam , linux-pci@vger.kernel.org, David Matlack Subject: Re: [PATCH v2] PCI/portdrv: Allow probing even without child services Message-ID: References: <20260209171535.v2.1.I5fd5d83f518681b3949d8ab2f16ba8244fd3e774@changeid> <20260716172641.GA100369@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: <20260716172641.GA100369@bhelgaas> On Thu, Jul 16, 2026 at 12:26:41PM -0500, Bjorn Helgaas wrote: > On Mon, Feb 09, 2026 at 05:15:35PM -0800, Brian Norris wrote: > > The PCIe port driver fails to probe if it finds no child services, > > presumably under the assumption that the driver is not useful in that > > case. However, the driver *can* still be useful for power management > > support -- namely, it still configures the port for runtime PM / D3, > > which may be important for allowing a bridge to enter low power modes. > > > > Thus, allow probe to succeed even if no IRQs and no child services are > > available. This also mirrors existing behavior for ports that have no > > PCIe capabilities, where we'd also probe successfully. > > > > This change is a bit more important after commit f5cd8a929c82 ("PCI: > > dwc: Remove MSI/MSIX capability for Root Port if iMSI-RX is used as MSI > > controller"), because it's common for some DWC-based systems to: > > > > 1. have only have the "aer" and "pcie_pme" port services available and > > 2. not define legacy INTx interrupts properly in their device tree. > > > > After commit f5cd8a929c82, such systems may fail > > pcie_init_service_irqs() and so exit with -ENODEV. > > > > Link: https://lore.kernel.org/all/nyada24tqwlkzdceyoxbzitzygvp4elvj5oajnqdwb33xkcdwk@76vnrx45fsfd/ > > Signed-off-by: Brian Norris > > Applied to pci/portdrv for v7.3, thank you! Some thoughts on the version now applied to pci/portdrv: * After this patch, the return value of pcie_device_init() is no longer evaluated, so that function should be changed to return void as part of this patch. * If no port services are initalized, e.g. because pcie_device_init() failed for all of them, the allocated IRQ vectors are not freed. They're hogged, which may be a problem on systems which only support very few IRQ vectors such as Sophgo SG2042: https://lore.kernel.org/r/0f42afefd9322779af5463b696c55b08d2296ea8.camel@iscas.ac.cn * It might be clearer to call pci_clear_master() directly in the if-block which is amended to "goto out". Then the "goto out" can be changed to a "return 0". It seems "if (!capabilities)" cannot happen through any other code path, so it's unclear why the "out" label is necessary. * There's a duplicate "have" in the commit message ("have only have"). Thanks, Lukas