Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S939990AbdDTIVC (ORCPT <rfc822;w@1wt.eu>);
        Thu, 20 Apr 2017 04:21:02 -0400
Received: from smtp5-g21.free.fr ([212.27.42.5]:16217 "EHLO smtp5-g21.free.fr"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751223AbdDTIU5 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 20 Apr 2017 04:20:57 -0400
Subject: Re: [RFC PATCH v0.2] PCI: Add support for tango PCIe host bridge
From: Mason <slash.tmp@free.fr>
To: Marc Zyngier <marc.zyngier@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Liviu Dudau <liviu.dudau@arm.com>,
        David Laight <david.laight@aculab.com>,
        linux-pci <linux-pci@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Thibaud Cornic <thibaud_cornic@sigmadesigns.com>,
        LKML <linux-kernel@vger.kernel.org>
References: <91db1f47-3024-9712-309a-fb4b21e42028@free.fr>
 <e5c0bace-fcbe-de3f-b76f-0fb672562e84@arm.com>
 <310db9dd-7db6-2106-2e53-f0083b2d3758@free.fr>
 <012f7fcb-eaeb-70dd-a1a9-06c213789d30@arm.com>
 <0502e180-5517-12d6-e3a1-bcea0da7e201@free.fr>
 <4edd799a-650c-0189-cd5c-e9fc18c5f8bc@arm.com>
 <30f662a6-5dab-515b-e35a-a312f3c7b509@free.fr>
 <5f81730d-fbe3-1f4c-de34-09bbfb893ee1@arm.com>
 <2b5eef4c-32f2-54f1-ca2f-f9426e68fb2c@free.fr>
 <67014006-a380-9e3b-c9af-a421052cb8e0@arm.com>
 <b59b81ea-bc1b-bff5-4a78-8a69538b0de3@free.fr>
 <bc5bf8ad-69ef-4f14-f450-e162ddb5af7c@arm.com>
 <241b130e-1fb7-ecd4-034e-eb02065ada66@free.fr>
 <37cd6172-b04e-fcad-18fc-4fbb26cc611b@arm.com>
 <87d48d57-5f9f-1b35-99da-ab39de2d3d48@free.fr>
Message-ID: <2003d851-e17e-1a43-3889-ec6e79e635e3@free.fr>
Date: Thu, 20 Apr 2017 10:20:31 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:51.0) Gecko/20100101
 Firefox/51.0 SeaMonkey/2.48
MIME-Version: 1.0
In-Reply-To: <87d48d57-5f9f-1b35-99da-ab39de2d3d48@free.fr>
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 791
Lines: 28

On 19/04/2017 13:19, Mason wrote:

> My biggest problem is that tango_unmask() is never called.

FTR, the missing incantation was:
Explicitly calling tango_{mask/unmask/ack} from the corresponding msi_{mask/unmask/ack}

Marc, I have one nagging doubt, wrt splitting MSI line selection
and MSI enable.

tango_irq_domain_alloc : finds an available MSI 'j' to allocate
tango_irq_domain_free : release MSI 'j'
tango_unmask : enable MSI 'j'
tango_mask : disable MSI 'j'

Is the following scenario guaranteed to never happen?

tango_irq_domain_alloc // alloc 0
tango_irq_domain_free  // free 0
tango_irq_domain_alloc // alloc 0
tango_unmask // enable 0
tango_unmask // enable 0 = NOP
tango_mask   // disable 0

In this theoretical scenario, we would be left with a non-functional
MSI 0.

Regards.