From c15982dfa8227f3e8fd2a6e2e13a009a9991d96c Mon Sep 17 00:00:00 2001
From: Murali Karicheri <m-karicheri2@ti.com>
Date: Mon, 8 Sep 2014 13:03:34 -0400
Subject: [PATCH] PCI: keystone: Limit MRSS for all downstream devices
Keystone PCIe controller has a limitation that memory read request size
must not exceed 256 bytes. This is a hardware limitation. Add a quirk to
force this limit on all downstream devices by updating MRRS.
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
.../devicetree/bindings/pci/pci-keystone.txt | 3 --
drivers/pci/host/pci-keystone.c | 45 +++++++++++++++++++
2 files changed, 45 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/pci/pci-keystone.txt b/Documentation/devicetree/bindings/pci/pci-keystone.txt
index ceb3e2424742..de9c475b66f4 100644
--- a/Documentation/devicetree/bindings/pci/pci-keystone.txt
+++ b/Documentation/devicetree/bindings/pci/pci-keystone.txt
@@ -63,6 +63,3 @@ Designware DT Properties not applicable for Keystone PCI
1. pcie_bus clock-names not used. Instead, a phandle to phys is used.
-Note for PCI driver usage
-=========================
-Driver requires pci=pcie_bus_perf in the bootargs for proper functioning.
diff --git a/drivers/pci/host/pci-keystone.c b/drivers/pci/host/pci-keystone.c
index c1cfaef7faf3..c58a9eb60141 100644
--- a/drivers/pci/host/pci-keystone.c
+++ b/drivers/pci/host/pci-keystone.c
@@ -42,8 +42,53 @@
/* DEV_STAT_CTRL */
#define PCIE_CAP_BASE 0x70
+/* PCIE controller device IDs */
+#define PCIE_RC_K2HK 0xb008
+#define PCIE_RC_K2E 0xb009
+#define PCIE_RC_K2L 0xb00a
+
#define to_keystone_pcie(x) container_of(x, struct keystone_pcie, pp)
+static void quirk_limit_mrrs(struct pci_dev *dev)
+{
+ struct pci_bus *bus = dev->bus;
+ struct pci_dev *bridge = bus->self;
+ static const struct pci_device_id rc_pci_devids[] = {
+ { PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2HK),
+ .class = PCI_CLASS_BRIDGE_PCI << 8, .class_mask = ~0, },
+ { PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2E),
+ .class = PCI_CLASS_BRIDGE_PCI << 8, .class_mask = ~0, },
+ { PCI_DEVICE(PCI_VENDOR_ID_TI, PCIE_RC_K2L),
+ .class = PCI_CLASS_BRIDGE_PCI << 8, .class_mask = ~0, },
+ { 0, },
+ };
+
+ if (pci_is_root_bus(bus))
+ return;
+
+ /* look for the host bridge */
+ while (!pci_is_root_bus(bus)) {
+ bridge = bus->self;
+ bus = bus->parent;
+ }
+
+ if (bridge) {
+ /*
+ * Keystone PCI controller has a h/w limitation of
+ * 256 bytes maximum read request size. It can't handle
+ * anything higher than this. So force this limit on
+ * all downstream devices.
+ */
+ if (pci_match_id(rc_pci_devids, bridge)) {
+ if (pcie_get_readrq(dev) > 256) {
+ dev_info(&dev->dev, "limiting MRRS to 256\n");
+ pcie_set_readrq(dev, 256);
+ }
+ }
+ }
+}
+DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, quirk_limit_mrrs);
+
static int ks_pcie_establish_link(struct keystone_pcie *ks_pcie)
{
struct pcie_port *pp = &ks_pcie->pp;