linux-kernel - [PATCH] PCI: MSI: Only use the generic MSI layer when domain is hierarchical

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Date:	Mon, 23 Nov 2015 14:27:06 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Phil Edworthy <phil.edworthy@...esas.com>,
	linux-kernel@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>
Subject: [PATCH] PCI: MSI: Only use the generic MSI layer when domain is hierarchical

Since d8a1cb757550 ("PCI/MSI: Let pci_msi_get_domain use struct
device::msi_domain"), we use the MSI domain associated to the PCI device.

But finding a MSI domain doesn't mean that the domain is implemented
using the generic MSI domain API, and a number of MSI controllers
are still using the arch_setup_msi_irq/arch_teardown_msi_irqs.

In order to avoid a firework on these systems, check that the domain
we just obtained is hierarchical. If not, don't use the generic MSI
stuff and stick with the old one. Not pretty, but reliable.

Another insentive to rework those drivers and phase out this API.

Reported-by: Phil Edworthy <phil.edworthy@...esas.com>
Tested-by: Phil Edworthy <phil.edworthy@...esas.com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 drivers/pci/msi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 53e4632..7eaa4c8 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -54,7 +54,7 @@ static int pci_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 	struct irq_domain *domain;
 
 	domain = pci_msi_get_domain(dev);
-	if (domain)
+	if (domain && irq_domain_is_hierarchy(domain))
 		return pci_msi_domain_alloc_irqs(domain, dev, nvec, type);
 
 	return arch_setup_msi_irqs(dev, nvec, type);
@@ -65,7 +65,7 @@ static void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
 	struct irq_domain *domain;
 
 	domain = pci_msi_get_domain(dev);
-	if (domain)
+	if (domain && irq_domain_is_hierarchy(domain))
 		pci_msi_domain_free_irqs(domain, dev);
 	else
 		arch_teardown_msi_irqs(dev);
-- 
2.1.4

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