PCI: rockchip: Don't advertise MSI-X in PCIe capabilities

[ Upstream commit a52587e ] The RK3399 PCIe endpoint controller cannot generate MSI-X IRQs. This is documented in the RK3399 technical reference manual (TRM) section 17.5.9 "Interrupt Support". MSI-X capability should therefore not be advertised. Remove the MSI-X capability by editing the capability linked-list. The previous entry is the MSI capability, therefore get the next entry from the MSI-X capability entry and set it as next entry for the MSI capability. This in effect removes MSI-X from the list. Linked list before : MSI cap -> MSI-X cap -> PCIe Device cap -> ... Linked list now : MSI cap -> PCIe Device cap -> ... Link: https://lore.kernel.org/r/20230418074700.1083505-11-rick.wertenbroek@gmail.com Fixes: cf590b0 ("PCI: rockchip: Add EP driver for Rockchip PCIe controller") Tested-by: Damien Le Moal <dlemoal@kernel.org> Signed-off-by: Rick Wertenbroek <rick.wertenbroek@gmail.com> Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
xanmod · Aug 3, 2023 · ed92b59 · ed92b59
1 parent 7b65231
commit ed92b59
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diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
@@ -508,6 +508,7 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
 	size_t max_regions;
 	struct pci_epc_mem_window *windows = NULL;
 	int err, i;
+	u32 cfg_msi, cfg_msix_cp;
 
 	ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
 	if (!ep)
@@ -583,6 +584,29 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
 
 	ep->irq_pci_addr = ROCKCHIP_PCIE_EP_DUMMY_IRQ_ADDR;
 
+	/*
+	 * MSI-X is not supported but the controller still advertises the MSI-X
+	 * capability by default, which can lead to the Root Complex side
+	 * allocating MSI-X vectors which cannot be used. Avoid this by skipping
+	 * the MSI-X capability entry in the PCIe capabilities linked-list: get
+	 * the next pointer from the MSI-X entry and set that in the MSI
+	 * capability entry (which is the previous entry). This way the MSI-X
+	 * entry is skipped (left out of the linked-list) and not advertised.
+	 */
+	cfg_msi = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
+				     ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
+
+	cfg_msi &= ~ROCKCHIP_PCIE_EP_MSI_CP1_MASK;
+
+	cfg_msix_cp = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
+					 ROCKCHIP_PCIE_EP_MSIX_CAP_REG) &
+					 ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK;
+
+	cfg_msi |= cfg_msix_cp;
+
+	rockchip_pcie_write(rockchip, cfg_msi,
+			    PCIE_EP_CONFIG_BASE + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
+
 	rockchip_pcie_write(rockchip, PCIE_CLIENT_CONF_ENABLE,
 			    PCIE_CLIENT_CONFIG);
 

diff --git a/drivers/pci/controller/pcie-rockchip.h b/drivers/pci/controller/pcie-rockchip.h
@@ -227,13 +227,18 @@
 #define ROCKCHIP_PCIE_EP_CMD_STATUS			0x4
 #define   ROCKCHIP_PCIE_EP_CMD_STATUS_IS		BIT(19)
 #define ROCKCHIP_PCIE_EP_MSI_CTRL_REG			0x90
+#define   ROCKCHIP_PCIE_EP_MSI_CP1_OFFSET		8
+#define   ROCKCHIP_PCIE_EP_MSI_CP1_MASK			GENMASK(15, 8)
 #define   ROCKCHIP_PCIE_EP_MSI_FLAGS_OFFSET		16
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_MMC_OFFSET		17
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_MMC_MASK		GENMASK(19, 17)
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_MME_OFFSET		20
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_MME_MASK		GENMASK(22, 20)
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_ME				BIT(16)
 #define   ROCKCHIP_PCIE_EP_MSI_CTRL_MASK_MSI_CAP	BIT(24)
+#define ROCKCHIP_PCIE_EP_MSIX_CAP_REG			0xb0
+#define   ROCKCHIP_PCIE_EP_MSIX_CAP_CP_OFFSET		8
+#define   ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK		GENMASK(15, 8)
 #define ROCKCHIP_PCIE_EP_DUMMY_IRQ_ADDR				0x1
 #define ROCKCHIP_PCIE_EP_PCI_LEGACY_IRQ_ADDR		0x3
 #define ROCKCHIP_PCIE_EP_FUNC_BASE(fn) \