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From 01649f43afb30df3c7450fd09c04a5a8ee6cb2c1 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Thu, 3 Feb 2022 15:51:41 +0000
Subject: [PATCH] net: phy: lan87xx: Decrease phy polling rate
Polling at 100Hz for 1.5s consumes quite a bit of kworker time with no
obvious benefit. Reduce that polling rate to ~6Hz.
To further save CPU and power, defer the next poll if no energy is
detected.
See: https://github.com/raspberrypi/linux/issues/4780
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/net/phy/smsc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -213,6 +213,8 @@ static int lan87xx_read_status(struct ph
return err;
if (!phydev->link && priv->energy_enable && phydev->irq == PHY_POLL) {
+ int energy_detected;
+
/* Disable EDPD to wake up PHY */
int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
if (rc < 0)
@@ -228,7 +230,7 @@ static int lan87xx_read_status(struct ph
*/
read_poll_timeout(phy_read, rc,
rc & MII_LAN83C185_ENERGYON || rc < 0,
- 10000, 1500000, true, phydev,
+ 150000, 1500000, true, phydev,
MII_LAN83C185_CTRL_STATUS);
if (rc < 0)
return rc;
@@ -238,10 +240,16 @@ static int lan87xx_read_status(struct ph
if (rc < 0)
return rc;
+ energy_detected = !!(rc & MII_LAN83C185_ENERGYON);
+
rc = phy_write(phydev, MII_LAN83C185_CTRL_STATUS,
rc | MII_LAN83C185_EDPWRDOWN);
if (rc < 0)
return rc;
+
+ /* Save CPU and power by deferring the next poll */
+ if (!energy_detected)
+ msleep(2000);
}
return err;
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