target/linux/bcm27xx/patches-5.15/950-0700-net-phy-lan87xx-Decrease-phy-polling-rate.patch

   1 From 01649f43afb30df3c7450fd09c04a5a8ee6cb2c1 Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Thu, 3 Feb 2022 15:51:41 +0000
   4 Subject: [PATCH] net: phy: lan87xx: Decrease phy polling rate
   5
   6 Polling at 100Hz for 1.5s consumes quite a bit of kworker time with no
   7 obvious benefit. Reduce that polling rate to ~6Hz.
   8
   9 To further save CPU and power, defer the next poll if no energy is
  10 detected.
  11
  12 See: https://github.com/raspberrypi/linux/issues/4780
  13
  14 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  15 ---
  16  drivers/net/phy/smsc.c | 10 +++++++++-
  17  1 file changed, 9 insertions(+), 1 deletion(-)
  18
  19 --- a/drivers/net/phy/smsc.c
  20 +++ b/drivers/net/phy/smsc.c
  21 @@ -220,6 +220,8 @@ static int lan87xx_read_status(struct ph
  22         int err = genphy_read_status(phydev);
  23
  24         if (!phydev->link && priv->energy_enable && phydev->irq == PHY_POLL) {
  25 +               int energy_detected;
  26 +
  27                 /* Disable EDPD to wake up PHY */
  28                 int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
  29                 if (rc < 0)
  30 @@ -235,7 +237,7 @@ static int lan87xx_read_status(struct ph
  31                  */
  32                 read_poll_timeout(phy_read, rc,
  33                                   rc & MII_LAN83C185_ENERGYON || rc < 0,
  34 -                                 10000, 1500000, true, phydev,
  35 +                                 150000, 1500000, true, phydev,
  36                                   MII_LAN83C185_CTRL_STATUS);
  37                 if (rc < 0)
  38                         return rc;
  39 @@ -245,10 +247,16 @@ static int lan87xx_read_status(struct ph
  40                 if (rc < 0)
  41                         return rc;
  42
  43 +               energy_detected = !!(rc & MII_LAN83C185_ENERGYON);
  44 +
  45                 rc = phy_write(phydev, MII_LAN83C185_CTRL_STATUS,
  46                                rc | MII_LAN83C185_EDPWRDOWN);
  47                 if (rc < 0)
  48                         return rc;
  49 +
  50 +               /* Save CPU and power by deferring the next poll */
  51 +               if (!energy_detected)
  52 +                       msleep(2000);
  53         }
  54
  55         return err;