[PATCH 5.15 25/98] net: dp83822: disable false carrier interrupt

Greg Kroah-Hartman
2022-07-05T12:21:11Z

From: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>

commit c96614eeab663646f57f67aa591e015abd8bd0ba upstream.

When unplugging an Ethernet cable, false carrier events were produced by
the PHY at a very high rate. Once the false carrier counter full, an
interrupt was triggered every few clock cycles until the cable was
replugged. This resulted in approximately 10k/s interrupts.

Since the false carrier counter (FCSCR) is never used, we can safely
disable this interrupt.

In addition to improving performance, this also solved MDIO read
timeouts I was randomly encountering with an i.MX8 fec MAC because of
the interrupt flood. The interrupt count and MDIO timeout fix were
tested on a v5.4.110 kernel.

Fixes: 87461f7a58ab ("net: phy: DP83822 initial driver submission")
Signed-off-by: Enguerrand de Ribaucourt <enguerrand.de-ribaucourt@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/phy/dp83822.c | 1 -
1 file changed, 1 deletion(-)

--- a/drivers/net/phy/dp83822.c
+++ b/drivers/net/phy/dp83822.c
@@ -229,7 +229,6 @@ static int dp83822_config_intr(struct ph
return misr_status;

misr_status |= (DP83822_RX_ERR_HF_INT_EN |
- DP83822_FALSE_CARRIER_HF_INT_EN |
DP83822_LINK_STAT_INT_EN |
DP83822_ENERGY_DET_INT_EN |
DP83822_LINK_QUAL_INT_EN);