Linux PCI subsystem development
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* [PATCH V2] PCI: Add ACS quirk for Loongson PCIe
@ 2025-04-03  4:07 Huacai Chen
  2025-04-14 13:50 ` Huacai Chen
  2025-04-17 20:28 ` Bjorn Helgaas
  0 siblings, 2 replies; 3+ messages in thread
From: Huacai Chen @ 2025-04-03  4:07 UTC (permalink / raw)
  To: Bjorn Helgaas, Lorenzo Pieralisi, Krzysztof Wilczyński,
	Rob Herring
  Cc: linux-pci, Jianmin Lv, Xuefeng Li, Huacai Chen, Jiaxun Yang,
	Huacai Chen, stable, Xianglai Li

Loongson PCIe Root Ports don't advertise an ACS capability, but they do
not allow peer-to-peer transactions between Root Ports. Add an ACS quirk
so each Root Port can be in a separate IOMMU group.

Cc: stable@vger.kernel.org
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
V2: Add more device ids.

 drivers/pci/quirks.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 8d610c17e0f2..eee96ad03614 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4995,6 +4995,18 @@ static int pci_quirk_brcm_acs(struct pci_dev *dev, u16 acs_flags)
 		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
 }
 
+static int pci_quirk_loongson_acs(struct pci_dev *dev, u16 acs_flags)
+{
+	/*
+	 * Loongson PCIe Root Ports don't advertise an ACS capability, but
+	 * they do not allow peer-to-peer transactions between Root Ports.
+	 * Allow each Root Port to be in a separate IOMMU group by masking
+	 * SV/RR/CR/UF bits.
+	 */
+	return pci_acs_ctrl_enabled(acs_flags,
+		PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF);
+}
+
 /*
  * Wangxun 40G/25G/10G/1G NICs have no ACS capability, but on
  * multi-function devices, the hardware isolates the functions by
@@ -5128,6 +5140,17 @@ static const struct pci_dev_acs_enabled {
 	{ PCI_VENDOR_ID_BROADCOM, 0x1762, pci_quirk_mf_endpoint_acs },
 	{ PCI_VENDOR_ID_BROADCOM, 0x1763, pci_quirk_mf_endpoint_acs },
 	{ PCI_VENDOR_ID_BROADCOM, 0xD714, pci_quirk_brcm_acs },
+	/* Loongson PCIe Root Ports */
+	{ PCI_VENDOR_ID_LOONGSON, 0x3C09, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x3C19, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x3C29, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A09, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A19, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A29, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A39, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A49, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A59, pci_quirk_loongson_acs },
+	{ PCI_VENDOR_ID_LOONGSON, 0x7A69, pci_quirk_loongson_acs },
 	/* Amazon Annapurna Labs */
 	{ PCI_VENDOR_ID_AMAZON_ANNAPURNA_LABS, 0x0031, pci_quirk_al_acs },
 	/* Zhaoxin multi-function devices */
-- 
2.47.1


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2025-04-03  4:07 [PATCH V2] PCI: Add ACS quirk for Loongson PCIe Huacai Chen
2025-04-14 13:50 ` Huacai Chen
2025-04-17 20:28 ` Bjorn Helgaas

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