mediatek: fix an irq handling issue

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/mediatek/patches-5.4/1010-pcie-mediatek-fix-clearing-interrupt-status.patch b/target/linux/mediatek/patches-5.4/1010-pcie-mediatek-fix-clearing-interrupt-status.patch
new file mode 100644 (file)
index 0000000..d3ef78d
--- /dev/null
+++ b/target/linux/mediatek/patches-5.4/1010-pcie-mediatek-fix-clearing-interrupt-status.patch
@@ -0,0 +1,24 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Fri, 4 Sep 2020 18:33:27 +0200
+Subject: [PATCH] pcie-mediatek: fix clearing interrupt status
+
+Clearing the status needs to happen after running the handler, otherwise
+we will get an extra spurious interrupt after the cause has been cleared
+
+Signed-off-by: Felix Fietkau <nbd@nbd.name>
+---
+
+--- a/drivers/pci/controller/pcie-mediatek.c
++++ b/drivers/pci/controller/pcie-mediatek.c
+@@ -616,10 +616,10 @@ static void mtk_pcie_intr_handler(struct
+       if (status & INTX_MASK) {
+               for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) {
+                       /* Clear the INTx */
+-                      writel(1 << bit, port->base + PCIE_INT_STATUS);
+                       virq = irq_find_mapping(port->irq_domain,
+                                               bit - INTX_SHIFT);
+                       generic_handle_irq(virq);
++                      writel(1 << bit, port->base + PCIE_INT_STATUS);
+               }
+       }
+