net: phy: broadcom: Add power down exit reset state delay

stable inclusion
from stable-5.10.27
commit e64a5a5b8e93a4064da38cde8b25e68750c60d54
bugzilla: 51493

--------------------------------

[ Upstream commit 7a1468ba ]

Per the datasheet, when we clear the power down bit, the PHY remains in
an internal reset state for 40us and then resume normal operation.
Account for that delay to avoid any issues in the future if
genphy_resume() changes.

Fixes: fe26821f ("net: phy: broadcom: Wire suspend/resume for BCM54810")
Signed-off-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: N  Weilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/net/phy/broadcom.c

@@ -332,6 +332,11 @@ static int bcm54xx_resume(struct phy_device *phydev)
 	if (ret < 0)
 		return ret;
 
+	/* Upon exiting power down, the PHY remains in an internal reset state
+	 * for 40us
+	 */
+	fsleep(40);
+
 	return bcm54xx_config_init(phydev);
 }