Subject: [4.5-rc7+ regression, bisected] libphy: PHY stmmac-0:ffffffff not found

From: Frank Schäfer <[email-masked]>
Date: Tue, 8 Mar 2016 19:06:23 +0100

commit 88f8b1bb41c6208f81b6a480244533ded7b59493
Author: Gabriel Fernandez <[email-masked]>
Date:   Mon Feb 29 17:18:22 2016 +0100

    stmmac: Fix 'eth0: No PHY found' regression
   
    This patch manages the case when you have an Ethernet MAC with
    a "fixed link", and not connected to a normal MDIO-managed PHY device.
   
    The test of phy_bus_name was not helpful because it was never affected
    and replaced by the mdio test node.
   
    Signed-off-by: Gabriel Fernandez <[email-masked]>
    Acked-by: Giuseppe Cavallaro <[email-masked]>
    Signed-off-by: David S. Miller <[email-masked]>

caused a regression on the Banana Pi M1 board:
...
[    1.573419] sun7i-dwmac 1c50000.ethernet: no reset control found
[    1.583476]  Ring mode enabled
[    1.590476]  No HW DMA feature register supported
[    1.595153]  Normal descriptors
[    1.606075]  TX Checksum insertion supported
...
[    9.430047] libphy: PHY stmmac-0:ffffffff not found
[    9.441829] eth0: Could not attach to PHY
[    9.452743] stmmac_open: Cannot attach to PHY (error: -19)

Reverting this commit makes it work again:

[    1.574459] sun7i-dwmac 1c50000.ethernet: no reset control found
[    1.584501]  Ring mode enabled
[    1.591491]  No HW DMA feature register supported
[    1.596169]  Normal descriptors
[    1.607076]  TX Checksum insertion supported
[    1.615766] sun7i-dwmac 1c50000.ethernet eth0: No MDIO subnode found
[    1.629108] libphy: stmmac: probed
[    1.636267] eth0: PHY ID 001cc915 at 0 IRQ POLL (stmmac-0:00) active
[    1.646446] eth0: PHY ID 001cc915 at 1 IRQ POLL (stmmac-0:01)
...
[   10.086423]  RX IPC Checksum Offload disabled
[   10.097628]  No MAC Management Counters available
[   14.084839] sun7i-dwmac 1c50000.ethernet eth0: Link is Up -
100Mbps/Full - flow control rx/tx

Regards,
Frank Schäfer