From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271AbbETMKF (ORCPT ); Wed, 20 May 2015 08:10:05 -0400 Received: from foss.arm.com ([217.140.101.70]:37933 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752888AbbETMJ6 (ORCPT ); Wed, 20 May 2015 08:09:58 -0400 Date: Wed, 20 May 2015 13:11:38 +0100 From: Marc Zyngier To: Robert Richter Cc: Thomas Gleixner , Jason Cooper , Tirumalesh Chalamarla , Radha Mohan Chintakuntla , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Robert Richter Subject: Re: [PATCH 1/4] arm64: gicv3: its: Encode domain number in PCI stream id Message-ID: <20150520131138.2c94a32a@why.wild-wind.fr.eu.org> In-Reply-To: <1430686172-18222-2-git-send-email-rric@kernel.org> References: <1430686172-18222-1-git-send-email-rric@kernel.org> <1430686172-18222-2-git-send-email-rric@kernel.org> Organization: ARM Ltd X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 3 May 2015 21:49:29 +0100 Robert Richter wrote: > From: Tirumalesh Chalamarla > > PCI stream ids need to consider pci bridge number to be unique on the > system. Using only bus and devfn can't do the trick in systems that > have multiple pci bridges. > > Signed-off-by: Tirumalesh Chalamarla > Signed-off-by: Robert Richter > --- > drivers/irqchip/irq-gic-v3-its.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index 9687f8afebff..e30b4de04c6c 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -1186,7 +1186,7 @@ static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data) > { > struct its_pci_alias *dev_alias = data; > > - dev_alias->dev_id = alias; > + dev_alias->dev_id = (pci_domain_nr(pdev->bus) << 16) | alias; > if (pdev != dev_alias->pdev) > dev_alias->count += its_pci_msi_vec_count(dev_alias->pdev); > This feels very scary. We're now assuming that the domain number will always be presented to the doorbell. What guarantee do we have that this is always the case, irrespective of the platform? Also, domains have no PCI reality, they are a Linux thing. And they can be "randomly" assigned, unless you force the domain in DT with a linux,pci-domain property. This looks even more wrong, specially considering ACPI. It really feels like we need a way to describe how the BDF numbering is augmented. We also need to guarantee that we get the actual bridge number, as opposed to the domain number. Thoughts? M. -- Without deviation from the norm, progress is not possible.