From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 9D612392838; Mon, 20 Jul 2026 20:44:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784580262; cv=none; b=H+j38twJKaG2RpEfsixOmsOgLYIgG5zg6SgKcR3F5kzRvV5hIx2tyj4Fz95Y2idRsekvk91DKpjgyyq4Wep2dJ+ve90POsWIqFjE+5md5eNPQwuOEc9y3AlbOGPLqZcqsQGCJgRWfpJ7eJUoLJ5CPgXN2WubBs2u2g5DN3VolJ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784580262; c=relaxed/simple; bh=AAL6FDCzJ8B3dc9n++X3RoIaRR3wsQfAZ0uInZu6yi0=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=Wzn+gKH54DeQGXNRRicOYyCKk6cPgqa2GDYTdJRoxXsxj8a4SQ6DF8YF1hmUa2zUplTzB3GP0+N10SK3+gvJ185slnvkUpAYWhjTIBbZwkYrJmf4RikbvPen3Q8aaYb5v+pmgvWWMEg8L/vlgIW4P8fqBakUyuNZsu5N7pEOWcU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XHKZh4sS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XHKZh4sS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 072A91F000E9; Mon, 20 Jul 2026 20:44:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784580261; bh=/b9pN6kht5qZu8FPQFKyxABDbD3yQrAOBxzoj1NBrEE=; h=Date:From:To:Cc:Subject:In-Reply-To; b=XHKZh4sSEgaIVPGVLzgfmpwvROdIfAukRQRecYiPxPEwoU6lEGN+fCdpNrmWs6OYx iY7u/vOID/tKk6woZVaOx1G3IO1NigPT0S1L4IqXBzvdD7fFp1jGR0Lfh6ntk6hUjp mYQDl73GNM540cLlCAH8/5MrUh8gw8z+w35sKHkvL+KEHsOgjl1jKCOQWHYkc8svEM azpUOCdNf8Bg3TotRES8u6gXBZGUFZwBmKKFwK+VXEICpbEy3Vr9XemyoOE7cz8poM m+MiJRXSC+F9BS1pbUPhgchdKJZKwptHaCAok/Q7fG2fiJfibrFyxvPcUHPDrrk+tH EhQiAlX5jX+QA== Date: Mon, 20 Jul 2026 15:44:19 -0500 From: Bjorn Helgaas To: Lukas Wunner , Brian Norris Cc: 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: <20260720204419.GA426578@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 Fri, Jul 17, 2026 at 10:26:53AM +0200, Lukas Wunner wrote: > 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 Seems like a good idea to free IRQ vectors we don't use. It *looks* like it should be safe to call pci_free_irq_vectors() here and then again in pcie_port_device_remove() if a port is removed, but Brian wasn't sure, and I didn't look any deeper than pci_disable_msix() and pci_disable_msi(). I guess if we did this we'd need to retain the pcie_device_init(). > * 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. It does look nicer that way. > * There's a duplicate "have" in the commit message ("have only have"). I fixed this on pci/portdrv. What do you think, Brian?