Hi Gerry,

Please see my comments / questions below.

On 11/6/14 21:20, Jiang Liu wrote:

Enhance PCI MSI core to support hierarchy irqdomain, so the common
code could be shared among architectures.

Signed-off-by: Jiang Liu <redacted>
---
Hi Thomas,
	These changes are a temporary solution, I'm working on another
patch set which will refine these interfaces, especially kill
arch_msi_irq_domain_{set|get}_hwirq().
Regards!
Gerry

Would the change includes the struct irqdomain_msi_data proposed by 
Thomas here (https://lkml.org/lkml/2014/11/6/210)?

[...]
+static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
+			    unsigned int nr_irqs, void *arg)
+{
+	int i, ret;
+	irq_hw_number_t hwirq = arch_msi_irq_domain_get_hwirq(arg);
+
+	if (irq_find_mapping(domain, hwirq) > 0)
+		return -EEXIST;
+
+	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
+	if (ret < 0)
+		return ret;
+

When executing irq_domain_alloc_irqs_parent(), it triggers the following 
warning message due to

	WARN_ON(desc->irq_data.chip == &no_irq_chip)

------------[ cut here ]------------
WARNING: CPU: 2 PID: 912 at kernel/irq/chip.c:734 
__irq_set_handler+0x138/0x13c()
Modules linked in: mlx4_core(+) rtc_efi efivarfs
CPU: 2 PID: 912 Comm: modprobe Not tainted 3.18.0-rc3-p2v5+ #53
Call trace:
[<fffffe00000963d4>] dump_backtrace+0x0/0x16c
[<fffffe0000096550>] show_stack+0x10/0x1c
[<fffffe000067545c>] dump_stack+0x74/0x98
[<fffffe00000b205c>] warn_slowpath_common+0x84/0xac
[<fffffe00000b2148>] warn_slowpath_null+0x14/0x20
[<fffffe00000ed968>] __irq_set_handler+0x134/0x13c
[<fffffe000042af14>] gic_irq_domain_map+0x4c/0xac
[<fffffe000042afd4>] gic_irq_domain_alloc+0x60/0x88
[<fffffe000042b374>] gicv2m_domain_alloc+0x30/0xa8
[<fffffe00000efc1c>] __irq_domain_alloc_irqs+0x144/0x30c
[<fffffe000042b58c>] gicv2m_setup_msi_irq+0xc0/0x118
[<fffffe000044548c>] arch_setup_msi_irq+0x34/0x60
[<fffffe0000445544>] arch_setup_msi_irqs+0x50/0xb0
[<fffffe0000445e3c>] pci_enable_msix+0x310/0x39c
[<fffffe0000445efc>] pci_enable_msix_range+0x34/0x9c
....

However, I think if we call irq_domain_set_hwirq_and_chip() in the 
msi_create_irq_domain() as suggested by Thomas, that should also fix 
this issue.

+	for (i = 0; i < nr_irqs; i++) {
+		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
+					      domain->host_data,
+					      (void *)(long)i);
+		__irq_set_handler(virq + i, handle_edge_irq, 0, "edge");
+	}

Is there are a way to specify other type of handler besides edge?

[...]
+static void msi_domain_activate(struct irq_domain *domain,
+				struct irq_data *irq_data)
+{
+	struct msi_msg msg;
+
+	/*
+	 * irq_data->chip_data is MSI/MSI-X offset.
+	 * MSI-X message is written per-IRQ, the offset is always 0.
+	 * MSI message denotes a contiguous group of IRQs, written for 0th IRQ.
+	 */
+	if (irq_data->chip_data)
+		return;

Actually, I am a bit confused with this comment here.  If you look at 
"/drivers/pci/msi.c: arch_setup_msi_irq()", it calls 
irq_set_chip_data(des->irq, chip) where chip is *msi_chip.

It looks like if the arch uses this API, it would conflict with what you 
have here where the irq_data->chip_data would be not NULL at the logic 
above, and would always return.

Thank you,

Suravee