Re: [PATCH net] net: phy: Avoid WARN_ON for PHY_NOLINK during resuming

From: Kunihiko Hayashi
Date: Fri Oct 21 2022 - 07:28:01 EST


On 2022/10/21 20:12, Heiner Kallweit wrote:
On 21.10.2022 11:35, Kunihiko Hayashi wrote:
Hi Heiner,

Thank you for your comment.

On 2022/10/21 17:38, Heiner Kallweit wrote:
On 21.10.2022 09:41, Kunihiko Hayashi wrote:
When resuming from sleep, if there is a time lag from link-down to
link-up
due to auto-negotiation, the phy status has been still PHY_NOLINK, so
WARN_ON dump occurs in mdio_bus_phy_resume(). For example, UniPhier AVE
ethernet takes about a few seconds to link up after resuming.

That autoneg takes some time is normal. If this would actually the root
cause then basically every driver should be affected. But it's not.

Although the auto-neg should happen normally, I'm not sure about other
platforms.

To avoid this issue, should remove PHY_NOLINK the WARN_ON conditions.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
---
drivers/net/phy/phy_device.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 57849ac0384e..c647d027bb5d 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -318,12 +318,12 @@ static __maybe_unused int
mdio_bus_phy_resume(struct
device *dev)
phydev->suspended_by_mdio_bus = 0;

/* If we managed to get here with the PHY state machine in a state
- * neither PHY_HALTED, PHY_READY nor PHY_UP, this is an indication
- * that something went wrong and we should most likely be using
- * MAC managed PM, but we are not.
+ * neither PHY_HALTED, PHY_READY, PHY_UP nor PHY_NOLINK, this is an
+ * indication that something went wrong and we should most likely
+ * be using MAC managed PM, but we are not.
*/

Did you read the comment you're changing? ave_resume() calls
phy_resume(),
so you should follow the advice in the comment.

I understand something is wrong with "PHY_NOLINK" here, and need to
investigate
the root cause of the phy state issue.

Best look at how phydev->mac_managed_pm is used in phylib and by MAC
drivers.

Thank you for the clue!
I'll try the flag and check the behavior of MAC/PHY.

Thank you,

---
Best Regards
Kunihiko Hayashi