[PATCH net] phy: dp83869: fix interrupts issue when using with an optical fiber sfp. to correctly clear the interrupts both status registers must be read.

[chalianis1@gmail.com]

From: Anis Chali <chalianis1@gmail.com>

from datasheet of dp83869hm
7.3.6 Interrupt
The DP83869HM can be configured to generate an interrupt when changes of internal status occur. The interrupt
allows a MAC to act upon the status in the PHY without polling the PHY registers. The interrupt source can be
selected through the interrupt registers, MICR (12h) and FIBER_INT_EN (C18h). The interrupt status can be
read from ISR (13h) and FIBER_INT_STTS (C19h) registers. Some interrupts are enabled by default and can
be disabled through register access. Both the interrupt status registers must be read in order to clear pending
interrupts. Until the pending interrupts are cleared, new interrupts may not be routed to the interrupt pin.

Fixes: 01db923e8377 ("net: phy: dp83869: Add TI dp83869 phy")

Cc: stable@vger.kernel.org
Signed-off-by: Anis Chali <chalianis1@gmail.com>
---
 drivers/net/phy/dp83869.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/phy/dp83869.c b/drivers/net/phy/dp83869.c
index a62cd838a9ea..1e8c20f387b8 100644
--- a/drivers/net/phy/dp83869.c
+++ b/drivers/net/phy/dp83869.c
@@ -41,6 +41,7 @@
 #define DP83869_IO_MUX_CFG	0x0170
 #define DP83869_OP_MODE		0x01df
 #define DP83869_FX_CTRL		0x0c00
+#define DP83869_FX_INT_STS		0x0c19
 
 #define DP83869_SW_RESET	BIT(15)
 #define DP83869_SW_RESTART	BIT(14)
@@ -195,6 +196,12 @@ static int dp83869_ack_interrupt(struct phy_device *phydev)
 	if (err < 0)
 		return err;
 
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_FIBRE_BIT, phydev->supported)) {
+		err = phy_read_mmd(phydev, DP83869_DEVADDR, DP83869_FX_INT_STS);
+		if (err < 0)
+			return err;		
+	}
+
 	return 0;
 }
 
-- 
2.49.0