linux-kernel - [PATCH v11 3/4] irqchip/loongarch-avec.c: return IRQ_SET_MASK_OK

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Message-ID: <20260203124522.2288900-4-zhangtianyang@loongson.cn>
Date: Tue,  3 Feb 2026 20:45:20 +0800
From: Tianyang Zhang <zhangtianyang@...ngson.cn>
To: chenhuacai@...nel.org,
	kernel@...0n.name,
	corbet@....net,
	alexs@...nel.org,
	si.yanteng@...ux.dev,
	tglx@...utronix.de,
	jiaxun.yang@...goat.com,
	maobibo@...ngson.cn
Cc: loongarch@...ts.linux.dev,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Tianyang Zhang <zhangtianyang@...ngson.cn>
Subject: [PATCH v11 3/4] irqchip/loongarch-avec.c: return IRQ_SET_MASK_OK_DONE when keep affinity

Interrupt redirection support requires a new redirect-domain, which will
appear as a child domain of avecintc. For each interrupt source, avecintc-domain
only provides the CPU/interrupt vector, while redirect-domain provides other
operations to synchronize interrupt affinity information among multiple cores.

When modifying the affinity of an interrupt associated with redirect-domain,
if the avecintc domain detects that the actual interrupt affinity has not changed,
then redirect-domain does not need to perform any operations.

To achieve the above purpose, when it is detected in avecintc_set_affinity()
that the current affinity remains valid, the return value is modified to
IRQ_SET_MASK_OK_DONE.

However, this introduces some compatibility issues, such as the new return
value causing msi_domain_set_affinity() to no longer perform irq_chip_write_msi_msg().
  1) When redirect exist in the system, the msg_address and msg_data no longer
change after the allocation phase, so it does not actually require updating the
MSI message info.
  2) When only avecintc exists in the system, the irq_domain_activate_irq
interface will be responsible for the initial configuration of the MSI message,
which is unconditional. After that, if unnecessary, no modification to the MSI
message is alse correctly.

Signed-off-by: Tianyang Zhang <zhangtianyang@...ngson.cn>
---
 drivers/irqchip/irq-loongarch-avec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-loongarch-avec.c b/drivers/irqchip/irq-loongarch-avec.c
index 70aa34439370..7bdf3f678db4 100644
--- a/drivers/irqchip/irq-loongarch-avec.c
+++ b/drivers/irqchip/irq-loongarch-avec.c
@@ -99,7 +99,7 @@ static int avecintc_set_affinity(struct irq_data *data, const struct cpumask *de
 			return -EBUSY;

 		if (cpu_online(adata->cpu) && cpumask_test_cpu(adata->cpu, dest))
-			return 0;
+			return IRQ_SET_MASK_OK_DONE;

 		cpumask_and(&intersect_mask, dest, cpu_online_mask);

-- 
2.41.0