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From: Kishon Vijay Abraham I <kishon@ti.com>
To: "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Wilczyński" <kw@linux.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>
Cc: <linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Kishon Vijay Abraham I <kishon@ti.com>,
	<devicetree@vger.kernel.org>
Subject: [PATCH v2 3/5] PCI: keystone: Add workaround for Errata #i2037 (AM65x SR 1.0)
Date: Fri, 26 Nov 2021 14:01:17 +0530	[thread overview]
Message-ID: <20211126083119.16570-4-kishon@ti.com> (raw)
In-Reply-To: <20211126083119.16570-1-kishon@ti.com>

Errata #i2037 in AM65x/DRA80xM Processors Silicon Revision 1.0
(SPRZ452D–July 2018–Revised December 2019 [1]) mentions when an
inbound PCIe TLP spans more than two internal AXI 128-byte bursts,
the bus may corrupt the packet payload and the corrupt data may
cause associated applications or the processor to hang.

The workaround for Errata #i2037 is to limit the maximum read
request size and maximum payload size to 128 bytes. Add workaround
for Errata #i2037 here. The errata and workaround is applicable
only to AM65x SR 1.0 and later versions of the silicon will have
this fixed.

[1] -> https://www.ti.com/lit/er/sprz452f/sprz452f.pdf

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
---
 drivers/pci/controller/dwc/pci-keystone.c | 42 +++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-keystone.c b/drivers/pci/controller/dwc/pci-keystone.c
index 13f03a97714c..52d20fe17ee9 100644
--- a/drivers/pci/controller/dwc/pci-keystone.c
+++ b/drivers/pci/controller/dwc/pci-keystone.c
@@ -35,6 +35,11 @@
 #define PCIE_DEVICEID_SHIFT	16
 
 /* Application registers */
+#define PID				0x000
+#define RTL				GENMASK(15, 11)
+#define RTL_SHIFT			11
+#define AM6_PCI_PG1_RTL_VER		0x15
+
 #define CMD_STATUS			0x004
 #define LTSSM_EN_VAL		        BIT(0)
 #define OB_XLAT_EN_VAL		        BIT(1)
@@ -105,6 +110,8 @@
 
 #define to_keystone_pcie(x)		dev_get_drvdata((x)->dev)
 
+#define PCI_DEVICE_ID_TI_AM654X		0xb00c
+
 struct ks_pcie_of_data {
 	enum dw_pcie_device_mode mode;
 	const struct dw_pcie_host_ops *host_ops;
@@ -528,7 +535,11 @@ static int ks_pcie_start_link(struct dw_pcie *pci)
 static void ks_pcie_quirk(struct pci_dev *dev)
 {
 	struct pci_bus *bus = dev->bus;
+	struct keystone_pcie *ks_pcie;
+	struct device *bridge_dev;
 	struct pci_dev *bridge;
+	u32 val;
+
 	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, },
@@ -540,6 +551,11 @@ static void ks_pcie_quirk(struct pci_dev *dev)
 		 .class = PCI_CLASS_BRIDGE_PCI << 8, .class_mask = ~0, },
 		{ 0, },
 	};
+	static const struct pci_device_id am6_pci_devids[] = {
+		{ PCI_DEVICE(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_AM654X),
+		 .class = PCI_CLASS_BRIDGE_PCI << 8, .class_mask = ~0, },
+		{ 0, },
+	};
 
 	if (pci_is_root_bus(bus))
 		bridge = dev;
@@ -565,6 +581,32 @@ static void ks_pcie_quirk(struct pci_dev *dev)
 			pcie_set_readrq(dev, 256);
 		}
 	}
+
+	/*
+	 * Memory transactions fail with PCI controller in AM654 PG1.0
+	 * when MRRS is set to more than 128 bytes. Force the MRRS to
+	 * 128 bytes in all downstream devices.
+	 */
+	if (pci_match_id(am6_pci_devids, bridge)) {
+		bridge_dev = pci_get_host_bridge_device(dev);
+		if (!bridge_dev && !bridge_dev->parent)
+			return;
+
+		ks_pcie = dev_get_drvdata(bridge_dev->parent);
+		if (!ks_pcie)
+			return;
+
+		val = ks_pcie_app_readl(ks_pcie, PID);
+		val &= RTL;
+		val >>= RTL_SHIFT;
+		if (val != AM6_PCI_PG1_RTL_VER)
+			return;
+
+		if (pcie_get_readrq(dev) > 128) {
+			dev_info(&dev->dev, "limiting MRRS to 128 bytes\n");
+			pcie_set_readrq(dev, 128);
+		}
+	}
 }
 DECLARE_PCI_FIXUP_ENABLE(PCI_ANY_ID, PCI_ANY_ID, ks_pcie_quirk);
 
-- 
2.17.1


  parent reply	other threads:[~2021-11-26  8:33 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-26  8:31 [PATCH v2 0/5] PCI: Keystone: Misc fixes for TI's AM65x PCIe Kishon Vijay Abraham I
2021-11-26  8:31 ` [PATCH v2 1/5] dt-bindings: PCI: ti,am65: Fix "ti,syscon-pcie-id"/"ti,syscon-pcie-mode" to take argument Kishon Vijay Abraham I
2021-11-27 23:13   ` Rob Herring
2021-11-29  4:03     ` Kishon Vijay Abraham I
2021-12-01 22:55   ` Rob Herring
2021-11-26  8:31 ` [PATCH v2 2/5] PCI: keystone: Use phandle argument from "ti,syscon-pcie-id"/"ti,syscon-pcie-mode" Kishon Vijay Abraham I
2021-11-26  8:31 ` Kishon Vijay Abraham I [this message]
2021-11-26  8:31 ` [PATCH v2 4/5] PCI: keystone: Add quirk to mark AM654 RC BAR flag as IORESOURCE_UNSET Kishon Vijay Abraham I
2022-01-04 15:57   ` Lorenzo Pieralisi
2022-01-11  6:23     ` Kishon Vijay Abraham I
2022-02-04 15:08       ` Kishon Vijay Abraham I
2022-02-08 11:53         ` Lorenzo Pieralisi
2022-02-08 16:20           ` Bjorn Helgaas
2022-01-04 18:25   ` Rob Herring
2021-11-26  8:31 ` [PATCH v2 5/5] PCI: keystone: Set DMA mask and coherent DMA mask Kishon Vijay Abraham I
2022-02-28 11:38   ` Christian Gmeiner
2022-01-04  9:02 ` [PATCH v2 0/5] PCI: Keystone: Misc fixes for TI's AM65x PCIe Kishon Vijay Abraham I
2022-01-07 10:56 ` (subset) " Lorenzo Pieralisi

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