linux-kernel - [PATCH V4 1/4] ACPI / PCI: fix LPIC IRQ model default PCI IRQ polarity

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Date:   Thu, 20 Oct 2022 16:22:02 +0800
From:   Jianmin Lv <lvjianmin@...ngson.cn>
To:     Thomas Gleixner <tglx@...utronix.de>, Marc Zyngier <maz@...nel.org>
Cc:     linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Len Brown <lenb@...nel.org>, rafael@...nel.org,
        linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: [PATCH V4 1/4] ACPI / PCI: fix LPIC IRQ model default PCI IRQ polarity

On LoongArch ACPI based systems, the PCI devices (e.g. sata
controlers and PCI-to-to PCI bridge controlers) existed in
Loongson chipsets output high-level interrupt signal to the
interrupt controller they connected to, while the IRQs are
active low from the perspective of PCI(in 2.2.6. Interrupt
Pins, "Interrupts on PCI are optional and defined as level
sensitive, asserted low), which means that the interrupt
output of PCI devices plugged into PCI-to-to PCI bridges of
Loongson chipset will be also converted to high-level. So
high level triggered type is required to be passed to
acpi_register_gsi() when creating mappings for PCI devices.

Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>
---
 drivers/acpi/pci_irq.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 08e15774fb9f..ff30ceca2203 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -387,13 +387,15 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
 	u8 pin;
 	int triggering = ACPI_LEVEL_SENSITIVE;
 	/*
-	 * On ARM systems with the GIC interrupt model, level interrupts
+	 * On ARM systems with the GIC interrupt model, or LoongArch
+	 * systems with the LPIC interrupt model, level interrupts
 	 * are always polarity high by specification; PCI legacy
 	 * IRQs lines are inverted before reaching the interrupt
 	 * controller and must therefore be considered active high
 	 * as default.
 	 */
-	int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ?
+	int polarity = acpi_irq_model == ACPI_IRQ_MODEL_GIC ||
+		       acpi_irq_model == ACPI_IRQ_MODEL_LPIC ?
 				      ACPI_ACTIVE_HIGH : ACPI_ACTIVE_LOW;
 	char *link = NULL;
 	char link_desc[16];
-- 
2.31.1