[PATCH v3 0/2] PCI: mediatek: Fixups for the IRQ handle routine and MT7622's class code

[PATCH v3 0/2] PCI: mediatek: Fixups for the IRQ handle routine and MT7622's class code

[honghui.zhang]

From: Honghui Zhang <honghui.zhang@mediatek.com>

Two fixups for mediatek's host bridge:
The first patch fixup the IRQ handle routine to avoid IRQ reentry which
may exist for both MT2712 and MT7622.
The second patch fixup class type for MT7622.

Change since v2:
 - Move the initialize of the iterate before the loop to fix an
   INTx IRQ issue in the first patch

Change since v1:
 - Add the second patch.
 - Make the first patch's commit message more standard.

Honghui Zhang (2):
  PCI: mediatek: Clear IRQ status after IRQ dispatched to avoid reentry
  PCI: mediatek: Fixup class type for MT7622

 drivers/pci/host/pcie-mediatek.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

-- 
2.6.4

[PATCH v3 1/2] PCI: mediatek: Clear IRQ status after IRQ dispatched to avoid reentry

[honghui.zhang]

From: Honghui Zhang <honghui.zhang@mediatek.com>

There maybe a same IRQ reentry scenario after IRQ received in current
IRQ handle flow:
	EP device		PCIe host driver	EP driver
1. issue an IRQ
			2. received IRQ
			3. clear IRQ status
			4. dispatch IRQ
						5. clear IRQ source
The IRQ status was not successfully cleared at step 2 since the IRQ
source was not cleared yet. So the PCIe host driver may receive the
same IRQ after step 5. Then there's an IRQ reentry occurred.
Even worse, if the reentry IRQ was not an IRQ that EP driver expected,
it may not handle the IRQ. Then we may run into the infinite loop from
step 2 to step 4.
Clear the IRQ status after IRQ have been dispatched to avoid the IRQ
reentry.
This patch also fix another INTx IRQ issue by initialize the iterate
before the loop. If an INTx IRQ re-occurred while we are dispatching
the INTx IRQ, then iterate may start from PCI_NUM_INTX + INTX_SHIFT
instead of INTX_SHIFT for the second time entering the
for_each_set_bit_from() loop.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
Acked-by: Ryder Lee <ryder.lee@mediatek.com>
---
 drivers/pci/host/pcie-mediatek.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c
index db93efd..fc29a9a 100644
--- a/drivers/pci/host/pcie-mediatek.c
+++ b/drivers/pci/host/pcie-mediatek.c
@@ -601,15 +601,16 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data)
 	struct mtk_pcie_port *port = (struct mtk_pcie_port *)data;
 	unsigned long status;
 	u32 virq;
-	u32 bit = INTX_SHIFT;
+	u32 bit;
 
 	while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) {
+		bit = INTX_SHIFT;
 		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);
+			/* Clear the INTx */
+			writel(1 << bit, port->base + PCIE_INT_STATUS);
 		}
 	}
 
@@ -619,10 +620,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data)
 
 			while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) {
 				for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) {
-					/* Clear the MSI */
-					writel(1 << bit, port->base + PCIE_IMSI_STATUS);
 					virq = irq_find_mapping(port->msi_domain, bit);
 					generic_handle_irq(virq);
+					/* Clear the MSI */
+					writel(1 << bit, port->base + PCIE_IMSI_STATUS);
 				}
 			}
 			/* Clear MSI interrupt status */
-- 
2.6.4

[PATCH v3 2/2] PCI: mediatek: Fixup class type for MT7622

[honghui.zhang]

From: Honghui Zhang <honghui.zhang@mediatek.com>

The host bridge of MT7622 has hardware code the class code to an
arbitrary, meaningless value, fix that.

Signed-off-by: Honghui Zhang <honghui.zhang@mediatek.com>
---
 drivers/pci/host/pcie-mediatek.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c
index fc29a9a..dcafeac 100644
--- a/drivers/pci/host/pcie-mediatek.c
+++ b/drivers/pci/host/pcie-mediatek.c
@@ -1175,3 +1175,15 @@ static struct platform_driver mtk_pcie_driver = {
 	},
 };
 builtin_platform_driver(mtk_pcie_driver);
+
+/* The host bridge of MT7622 advertises the wrong device class. */
+static void mtk_fixup_class(struct pci_dev *dev)
+{
+	dev->class = PCI_CLASS_BRIDGE_PCI << 8;
+}
+
+/*
+ * The HW default value of vendor id and device id for mt7622 are 0x0e8d,
+ * 0x3258, which are arbitrary, meaningless values.
+ */
+DECLARE_PCI_FIXUP_EARLY(0x0e8d, 0x3258, mtk_fixup_class);
-- 
2.6.4