pcie-rcar: try setting PCIe speed to 5 GT/s at boot

Initially, the PCIe link speed is set up only at 2.5 GT/s. For better performance, we're trying to increase link speed to 5 GT/s.

Based on the original patch by Grigory Kletsko
<[email protected]>.

Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against the 'next' branch of Bjorn Helgaas' 'pci.git' repo.

Changes in version 2:
- switched from the interrupt based speed change algorithm to polling with 1-second timeout, got rid of the now unneeded register/bit #define's;
- made rcar_pcie_force_speedup() *static*;
- moved the speed capability check to the start of rcar_pcie_force_speedup();
- adjusted the speed change in-progress check and the error message;
- read MACSR ony once during the speed change setup;
- print current link speed after any speed change outcome and when the speed is already 5 GT/s;
- removed the TODO comment;
- moved rcar_pcie_force_speedup() call to the start of rcar_pcie_enable();
- changed the patch authorship, updated the patch description accordingly.

 drivers/pci/host/pcie-rcar.c |   70 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

Index: pci/drivers/pci/host/pcie-rcar.c
===================================================================

drivers/pci/host/pcie-rcar.c +11 -0

@@ -84,8 +84,19 @@
 #define IDSETR1			0x011004
 #define TLCTLR			0x011048
 #define MACSR			0x011054
+#define  SPCHG			(1 << 5)
+#define  SPCHGFIN		(1 << 4)
+#define  SPCHGSUC		(1 << 7)
+#define  SPCHGFAIL		(1 << 6)
+#define  LINK_SPEED		(0xf << 16)
+#define  LINK_SPEED_2_5GTS	(1 << 16)
+#define  LINK_SPEED_5_0GTS	(2 << 16)
 #define MACCTLR			0x011058
+#define  SPEED_CHANGE		(1 << 24)
 #define  SCRAMBLE_DISABLE	(1 << 27)
+#define MACS2R			0x011078
+#define MACCGSPSETR		0x011084
+#define  SPCNGRSN		(1 << 31)
 
 /* R-Car H1 PHY */
 #define H1_PCIEPHYADRR		0x04000c

@@ -385,11 +396,70 @@ static int rcar_pcie_setup(struct list_h
 	return 1;
 }

drivers/pci/host/pcie-rcar.c +50 -0

+
+	if (rcar_pci_read_reg(pcie, MACCTLR) & SPEED_CHANGE) {
+		dev_err(pcie->dev, "Speed change is in progress\n");
+		return;
+	}
+
+	macsr = rcar_pci_read_reg(pcie, MACSR);
+	if ((macsr & LINK_SPEED) == LINK_SPEED_5_0GTS)
+		goto done;
+
+	/* Set target link speed to 5.0 GT/s */
+	rcar_rmw32(pcie, EXPCAP(12), PCI_EXP_LNKSTA_CLS,
+		   PCI_EXP_LNKSTA_CLS_5_0GB);
+
+	/* Set speed change reason as intentional factor */
+	rcar_rmw32(pcie, MACCGSPSETR, SPCNGRSN, 0);
+
+	/* Clear SPCHGFIN, SPCHGSUC, and SPCHGFAIL */
+	if (macsr & (SPCHGFIN | SPCHGSUC | SPCHGFAIL))
+		rcar_pci_write_reg(pcie, macsr, MACSR);
+
+	/* Start link speed change */
+	rcar_rmw32(pcie, MACCTLR, SPEED_CHANGE, SPEED_CHANGE);
+
+	while (timeout--) {
+		macsr = rcar_pci_read_reg(pcie, MACSR);
+		if (macsr & SPCHGFIN) {
+			/* Clear the interrupt bits */
+			rcar_pci_write_reg(pcie, macsr, MACSR);
+
+			if (macsr & SPCHGFAIL)
+				dev_err(pcie->dev, "Speed change failed\n");
+
+			goto done;
+		}
+
+		msleep(1);
+	};
+
+	dev_err(pcie->dev, "Speed change timed out\n");
+
+done:
+	/* Check speed */
+	dev_info(pcie->dev, "Current link speed is %s GT/s\n",
+		 (macsr & LINK_SPEED) == LINK_SPEED_5_0GTS ? "5" : "2.5");
+}
+
 static int rcar_pcie_enable(struct rcar_pcie *pcie)
 {
 	struct pci_bus *bus, *child;
 	LIST_HEAD(res);
 
+	/* Try setting 5 GT/s link speed */
+	rcar_pcie_force_speedup(pcie);
+
 	rcar_pcie_setup(&res, pcie);
 
 	pci_add_flags(PCI_REASSIGN_ALL_RSRC | PCI_REASSIGN_ALL_BUS);

Quoted 6 lines

Initially, the PCIe link speed is set up only at 2.5 GT/s. For better performance, we're trying to increase link speed to 5 GT/s.

Based on the original patch by Grigory Kletsko
<[email protected]>.

Quoted 4 lines

Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against the 'next' branch of Bjorn Helgaas' 'pci.git' repo.

Minor comment below, that not withstanding.

Acked-by Simon Horman <[email protected]>

Initially, the PCIe link speed is set up only at 2.5 GT/s. For better performance, we're trying to increase link speed to 5 GT/s.

Based on the original patch by Grigory Kletsko
<[email protected]>.

Signed-off-by Sergei Shtylyov <[email protected]>

---
The patch is against the 'next' branch of Bjorn Helgaas' 'pci.git' repo.

Changes in version 2:
- switched from the interrupt based speed change algorithm to polling with 1-second timeout, got rid of the now unneeded register/bit #define's;
- made rcar_pcie_force_speedup() *static*;
- moved the speed capability check to the start of rcar_pcie_force_speedup();
- adjusted the speed change in-progress check and the error message;
- read MACSR ony once during the speed change setup;
- print current link speed after any speed change outcome and when the speed is already 5 GT/s;
- removed the TODO comment;
- moved rcar_pcie_force_speedup() call to the start of rcar_pcie_enable();
- changed the patch authorship, updated the patch description accordingly.

 drivers/pci/host/pcie-rcar.c |   70 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

Index: pci/drivers/pci/host/pcie-rcar.c
===================================================================

drivers/pci/host/pcie-rcar.c +70 -1

@@ -84,8 +84,19 @@
 #define IDSETR1			0x011004
 #define TLCTLR			0x011048
 #define MACSR			0x011054
+#define  SPCHG			(1 << 5)
+#define  SPCHGFIN		(1 << 4)
+#define  SPCHGSUC		(1 << 7)
+#define  SPCHGFAIL		(1 << 6)
+#define  LINK_SPEED		(0xf << 16)
+#define  LINK_SPEED_2_5GTS	(1 << 16)
+#define  LINK_SPEED_5_0GTS	(2 << 16)
 #define MACCTLR			0x011058
+#define  SPEED_CHANGE		(1 << 24)
 #define  SCRAMBLE_DISABLE	(1 << 27)
+#define MACS2R			0x011078
+#define MACCGSPSETR		0x011084
+#define  SPCNGRSN		(1 << 31)
 
 /* R-Car H1 PHY */
 #define H1_PCIEPHYADRR		0x04000c

@@ -385,11 +396,70 @@ static int rcar_pcie_setup(struct list_h
 	return 1;
 }
 
+static void rcar_pcie_force_speedup(struct rcar_pcie *pcie)
+{
+	unsigned int timeout = 1000;
+	u32 macsr;
+
+	if ((rcar_pci_read_reg(pcie, MACS2R) & LINK_SPEED) != LINK_SPEED_5_0GTS)
+		return;
+
+	dev_info(pcie->dev, "Trying speed up to 5 GT/s\n");
+
+	if (rcar_pci_read_reg(pcie, MACCTLR) & SPEED_CHANGE) {
+		dev_err(pcie->dev, "Speed change is in progress\n");
+		return;
+	}
+
+	macsr = rcar_pci_read_reg(pcie, MACSR);
+	if ((macsr & LINK_SPEED) == LINK_SPEED_5_0GTS)
+		goto done;
+
+	/* Set target link speed to 5.0 GT/s */
+	rcar_rmw32(pcie, EXPCAP(12), PCI_EXP_LNKSTA_CLS,
+		   PCI_EXP_LNKSTA_CLS_5_0GB);
+
+	/* Set speed change reason as intentional factor */
+	rcar_rmw32(pcie, MACCGSPSETR, SPCNGRSN, 0);
+
+	/* Clear SPCHGFIN, SPCHGSUC, and SPCHGFAIL */
+	if (macsr & (SPCHGFIN | SPCHGSUC | SPCHGFAIL))
+		rcar_pci_write_reg(pcie, macsr, MACSR);
+
+	/* Start link speed change */
+	rcar_rmw32(pcie, MACCTLR, SPEED_CHANGE, SPEED_CHANGE);
+
+	while (timeout--) {
+		macsr = rcar_pci_read_reg(pcie, MACSR);
+		if (macsr & SPCHGFIN) {
+			/* Clear the interrupt bits */
+			rcar_pci_write_reg(pcie, macsr, MACSR);
+
+			if (macsr & SPCHGFAIL)
+				dev_err(pcie->dev, "Speed change failed\n");
+
+			goto done;
+		}
+
+		msleep(1);
+	};
+
+	dev_err(pcie->dev, "Speed change timed out\n");
+
+done:
+	/* Check speed */
+	dev_info(pcie->dev, "Current link speed is %s GT/s\n",
+		 (macsr & LINK_SPEED) == LINK_SPEED_5_0GTS ? "5" : "2.5");
+}
+
 static int rcar_pcie_enable(struct rcar_pcie *pcie)
 {
 	struct pci_bus *bus, *child;
 	LIST_HEAD(res);
 
+	/* Try setting 5 GT/s link speed */
+	rcar_pcie_force_speedup(pcie);
+
 	rcar_pcie_setup(&res, pcie);
 
 	pci_add_flags(PCI_REASSIGN_ALL_RSRC | PCI_REASSIGN_ALL_BUS);
 
--

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Quoted 7 lines

Initially, the PCIe link speed is set up only at 2.5 GT/s. For better performance, we're trying to increase link speed to 5 GT/s.

Based on the original patch by Grigory Kletsko
<[email protected]>.

Signed-off-by Sergei Shtylyov <[email protected]>

I addressed Simon's comment for you, added his ack, and applied this to pci/host-rcar for v4.9.