[openwrt/openwrt] realtek: clean up rtl838x MDIO busy wait loop

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/81e3017609be0ffa85c7ba430734e47519186481

commit 81e3017609be0ffa85c7ba430734e47519186481
Author: Jan Hoffmann <jan at 3e8.eu>
AuthorDate: Sat Jul 23 22:53:16 2022 +0200

    realtek: clean up rtl838x MDIO busy wait loop
    
    Don't use udelay to allow other kernel tasks to execute if the kernel
    has been built without preemption. Also determine the timeout based on
    jiffies instead of loop iterations.
    
    This is especially important on devices containing a watchdog with a
    short timeout. Without this change, the watchdog is not serviced during
    PHY patching which can take multiple seconds.
    
    Tested-by: Birger Koblitz <mail at birger-koblitz.de>
    Signed-off-by: Jan Hoffmann <jan at 3e8.eu>
---
 .../files-5.10/drivers/net/dsa/rtl83xx/rtl838x.c   | 37 +++++++++++++---------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.c b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.c
index cdf1766778..524594d725 100644
--- a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.c
+++ b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.c
@@ -1805,13 +1805,20 @@ irqreturn_t rtl838x_switch_irq(int irq, void *dev_id)
 
 int rtl838x_smi_wait_op(int timeout)
 {
-	do {
-		timeout--;
-		udelay(10);
-	} while ((sw_r32(RTL838X_SMI_ACCESS_PHY_CTRL_1) & 0x1) && (timeout >= 0));
-	if (timeout <= 0)
-		return -1;
-	return 0;
+	unsigned long end = jiffies + usecs_to_jiffies(timeout);
+
+	while (1) {
+		if (!(sw_r32(RTL838X_SMI_ACCESS_PHY_CTRL_1) & 0x1))
+			return 0;
+
+		if (time_after(jiffies, end))
+			break;
+
+		usleep_range(10, 20);
+	}
+
+	pr_err("rtl838x_smi_wait_op: timeout\n");
+	return -1;
 }
 
 /*
@@ -1832,7 +1839,7 @@ int rtl838x_read_phy(u32 port, u32 page, u32 reg, u32 *val)
 
 	mutex_lock(&smi_lock);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	sw_w32_mask(0xffff0000, port << 16, RTL838X_SMI_ACCESS_PHY_CTRL_2);
@@ -1842,7 +1849,7 @@ int rtl838x_read_phy(u32 port, u32 page, u32 reg, u32 *val)
 	sw_w32(v | park_page, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 	sw_w32_mask(0, 1, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	*val = sw_r32(RTL838X_SMI_ACCESS_PHY_CTRL_2) & 0xffff;
@@ -1868,7 +1875,7 @@ int rtl838x_write_phy(u32 port, u32 page, u32 reg, u32 val)
 		return -ENOTSUPP;
 
 	mutex_lock(&smi_lock);
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	sw_w32(BIT(port), RTL838X_SMI_ACCESS_PHY_CTRL_0);
@@ -1881,7 +1888,7 @@ int rtl838x_write_phy(u32 port, u32 page, u32 reg, u32 val)
 	sw_w32(v | park_page, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 	sw_w32_mask(0, 1, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	mutex_unlock(&smi_lock);
@@ -1901,7 +1908,7 @@ int rtl838x_read_mmd_phy(u32 port, u32 addr, u32 reg, u32 *val)
 
 	mutex_lock(&smi_lock);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	sw_w32(1 << port, RTL838X_SMI_ACCESS_PHY_CTRL_0);
@@ -1916,7 +1923,7 @@ int rtl838x_read_mmd_phy(u32 port, u32 addr, u32 reg, u32 *val)
 	v = 1 << 1 | 0 << 2 | 1;
 	sw_w32(v, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	*val = sw_r32(RTL838X_SMI_ACCESS_PHY_CTRL_2) & 0xffff;
@@ -1940,7 +1947,7 @@ int rtl838x_write_mmd_phy(u32 port, u32 addr, u32 reg, u32 val)
 	val &= 0xffff;
 	mutex_lock(&smi_lock);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	sw_w32(1 << port, RTL838X_SMI_ACCESS_PHY_CTRL_0);
@@ -1954,7 +1961,7 @@ int rtl838x_write_mmd_phy(u32 port, u32 addr, u32 reg, u32 val)
 	v = 1 << 1 | 1 << 2 | 1;
 	sw_w32(v, RTL838X_SMI_ACCESS_PHY_CTRL_1);
 
-	if (rtl838x_smi_wait_op(10000))
+	if (rtl838x_smi_wait_op(100000))
 		goto timeout;
 
 	mutex_unlock(&smi_lock);