[PATCH AUTOSEL 4.19 260/671] net: phy: don't clear BMCR in genphy_soft_reset

Sasha Levin
2020-01-16T17:03:15Z

From: Heiner Kallweit <hkallweit1@gmail.com>

[ Upstream commit d29f5aa0bc0c321e1b9e4658a2a7e08e885da52a ]

So far we effectively clear the BMCR register. Some PHY's can deal
with this (e.g. because they reset BMCR to a default as part of a
soft-reset) whilst on others this causes issues because e.g. the
autoneg bit is cleared. Marvell is an example, see also thread [0].
So let's be a little bit more gentle and leave all bits we're not
interested in as-is. This change is needed for PHY drivers to
properly deal with the original patch.

[0] https://marc.info/?t=155264050700001&r=1&w=2

Fixes: 6e2d85ec0559 ("net: phy: Stop with excessive soft reset")
Tested-by: Phil Reid <preid@electromag.com.au>
Tested-by: liweihang <liweihang@hisilicon.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/phy/phy_device.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 9c7e51443f6b..ae40d8137fd2 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1657,7 +1657,7 @@ int genphy_soft_reset(struct phy_device *phydev)
{
int ret;

- ret = phy_write(phydev, MII_BMCR, BMCR_RESET);
+ ret = phy_set_bits(phydev, MII_BMCR, BMCR_RESET);
if (ret < 0)
return ret;

--
2.20.1