Merge branch 'net-mvmdio-performance-related-improvements'

Tobias Waldekranz says:

====================
net: mvmdio: Performance related improvements

Observations of the XMDIO bus on a CN9130-based system during a
firmware download showed a very low bus utilization, which stemmed
from the 150us (10x the average access time) sleep which would take
place when the first poll did not succeed.

With this series in place, bus throughput increases by about 10x,
multiplied by whatever gain you are able to extract from running the
MDC at a higher frequency (hardware dependent).
====================

Link: https://lore.kernel.org/r/20231204100811.2708884-1-tobias@waldekranz.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/mvmdio.c

@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
@@ -52,17 +53,19 @@
 #define  MVMDIO_XSMI_BUSY		BIT(30)
 #define MVMDIO_XSMI_ADDR_REG		0x8
 
+#define MVMDIO_XSMI_CFG_REG		0xc
+#define  MVMDIO_XSMI_CLKDIV_MASK	0x3
+#define  MVMDIO_XSMI_CLKDIV_256		0x0
+#define  MVMDIO_XSMI_CLKDIV_64		0x1
+#define  MVMDIO_XSMI_CLKDIV_32		0x2
+#define  MVMDIO_XSMI_CLKDIV_8		0x3
+
 /*
  * SMI Timeout measurements:
  * - Kirkwood 88F6281 (Globalscale Dreamplug): 45us to 95us (Interrupt)
  * - Armada 370       (Globalscale Mirabox):   41us to 43us (Polled)
  */
 #define MVMDIO_SMI_TIMEOUT		1000 /* 1000us = 1ms */
-#define MVMDIO_SMI_POLL_INTERVAL_MIN	45
-#define MVMDIO_SMI_POLL_INTERVAL_MAX	55
-
-#define MVMDIO_XSMI_POLL_INTERVAL_MIN	150
-#define MVMDIO_XSMI_POLL_INTERVAL_MAX	160
 
 struct orion_mdio_dev {
 	void __iomem *regs;
@@ -84,8 +87,6 @@ enum orion_mdio_bus_type {
 
 struct orion_mdio_ops {
 	int (*is_done)(struct orion_mdio_dev *);
-	unsigned int poll_interval_min;
-	unsigned int poll_interval_max;
 };
 
 /* Wait for the SMI unit to be ready for another operation
@@ -94,34 +95,23 @@ static int orion_mdio_wait_ready(const struct orion_mdio_ops *ops,
 				 struct mii_bus *bus)
 {
 	struct orion_mdio_dev *dev = bus->priv;
-	unsigned long timeout = usecs_to_jiffies(MVMDIO_SMI_TIMEOUT);
-	unsigned long end = jiffies + timeout;
-	int timedout = 0;
+	unsigned long timeout;
+	int done;
 
-	while (1) {
-	        if (ops->is_done(dev))
+	if (dev->err_interrupt <= 0) {
+		if (!read_poll_timeout_atomic(ops->is_done, done, done, 2,
+					      MVMDIO_SMI_TIMEOUT, false, dev))
+			return 0;
+	} else {
+		/* wait_event_timeout does not guarantee a delay of at
+		 * least one whole jiffie, so timeout must be no less
+		 * than two.
+		 */
+		timeout = max(usecs_to_jiffies(MVMDIO_SMI_TIMEOUT), 2);
+
+		if (wait_event_timeout(dev->smi_busy_wait,
+				       ops->is_done(dev), timeout))
 			return 0;
-	        else if (timedout)
-			break;
-
-	        if (dev->err_interrupt <= 0) {
-			usleep_range(ops->poll_interval_min,
-				     ops->poll_interval_max);
-
-			if (time_is_before_jiffies(end))
-				++timedout;
-	        } else {
-			/* wait_event_timeout does not guarantee a delay of at
-			 * least one whole jiffie, so timeout must be no less
-			 * than two.
-			 */
-			if (timeout < 2)
-				timeout = 2;
-			wait_event_timeout(dev->smi_busy_wait,
-				           ops->is_done(dev), timeout);
-
-			++timedout;
-	        }
 	}
 
 	dev_err(bus->parent, "Timeout: SMI busy for too long\n");
@@ -135,8 +125,6 @@ static int orion_mdio_smi_is_done(struct orion_mdio_dev *dev)
 
 static const struct orion_mdio_ops orion_mdio_smi_ops = {
 	.is_done = orion_mdio_smi_is_done,
-	.poll_interval_min = MVMDIO_SMI_POLL_INTERVAL_MIN,
-	.poll_interval_max = MVMDIO_SMI_POLL_INTERVAL_MAX,
 };
 
 static int orion_mdio_smi_read(struct mii_bus *bus, int mii_id,
@@ -194,8 +182,6 @@ static int orion_mdio_xsmi_is_done(struct orion_mdio_dev *dev)
 
 static const struct orion_mdio_ops orion_mdio_xsmi_ops = {
 	.is_done = orion_mdio_xsmi_is_done,
-	.poll_interval_min = MVMDIO_XSMI_POLL_INTERVAL_MIN,
-	.poll_interval_max = MVMDIO_XSMI_POLL_INTERVAL_MAX,
 };
 
 static int orion_mdio_xsmi_read_c45(struct mii_bus *bus, int mii_id,
@@ -246,6 +232,40 @@ static int orion_mdio_xsmi_write_c45(struct mii_bus *bus, int mii_id,
 	return 0;
 }
 
+static void orion_mdio_xsmi_set_mdc_freq(struct mii_bus *bus)
+{
+	struct orion_mdio_dev *dev = bus->priv;
+	struct clk *mg_core;
+	u32 div, freq, cfg;
+
+	if (device_property_read_u32(bus->parent, "clock-frequency", &freq))
+		return;
+
+	mg_core = of_clk_get_by_name(bus->parent->of_node, "mg_core_clk");
+	if (IS_ERR(mg_core)) {
+		dev_err(bus->parent,
+			"MG core clock unknown, not changing MDC frequency");
+		return;
+	}
+
+	div = clk_get_rate(mg_core) / (freq + 1) + 1;
+	clk_put(mg_core);
+
+	if (div <= 8)
+		div = MVMDIO_XSMI_CLKDIV_8;
+	else if (div <= 32)
+		div = MVMDIO_XSMI_CLKDIV_32;
+	else if (div <= 64)
+		div = MVMDIO_XSMI_CLKDIV_64;
+	else
+		div = MVMDIO_XSMI_CLKDIV_256;
+
+	cfg = readl(dev->regs + MVMDIO_XSMI_CFG_REG);
+	cfg &= ~MVMDIO_XSMI_CLKDIV_MASK;
+	cfg |= div;
+	writel(cfg, dev->regs + MVMDIO_XSMI_CFG_REG);
+}
+
 static irqreturn_t orion_mdio_err_irq(int irq, void *dev_id)
 {
 	struct orion_mdio_dev *dev = dev_id;
@@ -324,6 +344,9 @@ static int orion_mdio_probe(struct platform_device *pdev)
 			dev_warn(&pdev->dev,
 				 "unsupported number of clocks, limiting to the first "
 				 __stringify(ARRAY_SIZE(dev->clk)) "\n");
+
+		if (type == BUS_TYPE_XSMI)
+			orion_mdio_xsmi_set_mdc_freq(bus);
 	} else {
 		dev->clk[0] = clk_get(&pdev->dev, NULL);
 		if (PTR_ERR(dev->clk[0]) == -EPROBE_DEFER) {