[tip: irq/msi] irqchip/gic-v3-its: Set IRQ_DOMAIN_FLAG_MSI_IMMUTABLE for ITS

["tip-bot2 for Frank Li" <tip-bot2@linutronix.de>]

The following commit has been merged into the irq/msi branch of tip:

Commit-ID:     fd120c38fefd26f1e23f308141f52098c1bbfb31
Gitweb:        https://git.kernel.org/tip/fd120c38fefd26f1e23f308141f52098c1bbfb31
Author:        Frank Li <Frank.Li@nxp.com>
AuthorDate:    Mon, 14 Apr 2025 14:30:57 -04:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 07 May 2025 17:49:00 +02:00

irqchip/gic-v3-its: Set IRQ_DOMAIN_FLAG_MSI_IMMUTABLE for ITS

Set the IRQ_DOMAIN_FLAG_MSI_IMMUTABLE flag for ITS, as it does not change
the address/data pair after setup.

Ensure compatibility with MSI users, such as PCIe Endpoint Doorbell, which
require the address/data pair to remain unchanged. Enable PCIe endpoints to
use ITS for triggering doorbells from the PCIe Root Complex (RC) side.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250414-ep-msi-v18-3-f69b49917464@nxp.com

---
 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 0115ad6..fd6e7c1 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -5140,7 +5140,7 @@ static int its_init_domain(struct its_node *its)
 	irq_domain_update_bus_token(inner_domain, DOMAIN_BUS_NEXUS);
 
 	inner_domain->msi_parent_ops = &gic_v3_its_msi_parent_ops;
-	inner_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
+	inner_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT | IRQ_DOMAIN_FLAG_MSI_IMMUTABLE;
 
 	return 0;
 }