From 01649f43afb30df3c7450fd09c04a5a8ee6cb2c1 Mon Sep 17 00:00:00 2001 From: Phil Elwell 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 --- 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 @@ -218,6 +218,8 @@ static int lan87xx_read_status(struct ph int err = genphy_read_status(phydev); if (!phydev->link && priv->energy_enable) { + int energy_detected; + /* Disable EDPD to wake up PHY */ int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS); if (rc < 0) @@ -233,7 +235,7 @@ 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; @@ -243,10 +245,16 @@ 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;