net: phy: c45-tjaxx: add delay between MDIO write and read in soft_reset

In application note (AN13663) for TJA1120, on page 30, there's a figure
with average PHY startup timing values following software reset.
The time it takes for SMI to become operational after software reset
ranges roughly from 500 us to 1500 us.

This commit adds 2000 us delay after MDIO write which triggers software
reset. Without this delay, soft_reset function returns an error and
prevents successful PHY init.

Cc: stable@vger.kernel.org
Fixes: b050f2f15e04 ("phy: nxp-c45: add driver for tja1103")
Signed-off-by: Milos Reljin <milos_reljin@outlook.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/AM8P250MB0124D258E5A71041AF2CC322E1E32@AM8P250MB0124.EURP250.PROD.OUTLOOK.COM
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/phy/nxp-c45-tja11xx.c b/drivers/net/phy/nxp-c45-tja11xx.c
index 323717a4821fc9e5842386d023bc5d9264594304..34231b5b9175480d6341807d8410c4abbb55c200 100644 (file)
--- a/drivers/net/phy/nxp-c45-tja11xx.c
+++ b/drivers/net/phy/nxp-c45-tja11xx.c
@@ -1297,6 +1297,8 @@ static int nxp_c45_soft_reset(struct phy_device *phydev)
        if (ret)
                return ret;
 
+       usleep_range(2000, 2050);
+
        return phy_read_mmd_poll_timeout(phydev, MDIO_MMD_VEND1,
                                         VEND1_DEVICE_CONTROL, ret,
                                         !(ret & DEVICE_CONTROL_RESET), 20000,