On Sat, 1 Feb 2020 21:26:54 +0100
Heiner Kallweit [off-list ref] wrote:

On 01.02.2020 11:25, Ivan Vecera wrote:

quoted

On Fri, 31 Jan 2020 21:50:48 +0100
Heiner Kallweit [off-list ref] wrote:
  

quoted

quoted

0x7949
[   24.154174] xgene-mii-rgmii:03: genphy_update_link(), line: 1927, link: 0

. supressed 3 same messages in T0+1,2,3s

[   28.609822] xgene-mii-rgmii:03: genphy_update_link(), line: 1895, link: 0
[   28.629906] xgene-mii-rgmii:03: genphy_update_link(), line: 1917, status:
0x7969
^^^^^^^^^^^^^^^ detected BMSR_ANEGCOMPLETE but not BMSR_LSTATUS
[   28.644590] xgene-mii-rgmii:03: genphy_update_link(), line: 1921, status:
0x796d
^^^^^^^^^^^^^^^ here is detected BMSR_ANEGCOMPLETE and BMSR_LSTATUS
[   28.658681] xgene-mii-rgmii:03: genphy_update_link(), line: 1927, link: 1
    

I see, thanks. Strange behavior of the PHY. Did you test also with other PHY's
whether they behave the same?  

Yeah, it's strange... we could try different PHYs but anyway the double read was
removed for polling mode to detect momentary link drops but it make sense only
when phy->link is not 0. Thoughts?

Ivan
  

I checked with the internal PHY of a Realtek NIC and it showed the same behavior.
So it seems that Realtek PHY's behave like this in general. Therefore I'm fine
with the patch. Just two things:
- Add details about this quirky behavior to the commit description.
- Resubmit annotated as net-next once net-next is open again. It's an improvement,
  not a fix.

LGTM. Thanks for confirmation.

Ivan