Re: [PATCH] net: ethernet: fec: Clear stale flag in IEVENT register before MII transfers

[Marian Cichy]

On 12/9/20 5:51 PM, Uwe Kleine-König wrote:

Hi Andrew,

On Wed, Dec 09, 2020 at 03:44:13PM +0100, Andrew Lunn wrote:

On Wed, Dec 09, 2020 at 11:29:59AM +0100, Uwe Kleine-König wrote:
Do you have

ommit 1e6114f51f9d4090390fcec2f5d67d8cc8dc4bfc
Author: Greg Ungerer <g...@linux-m68k.org>
Date:   Wed Oct 28 15:22:32 2020 +1000

     net: fec: fix MDIO probing for some FEC hardware blocks

Some (apparently older) versions of the FEC hardware block do not like

     the MMFR register being cleared to avoid generation of MII events at
     initialization time. The action of clearing this register results in no
     future MII events being generated at all on the problem block. This means
     the probing of the MDIO bus will find no PHYs.

Create a quirk that can be checked at the FECs MII init time so that

     the right thing is done. The quirk is set as appropriate for the FEC
     hardware blocks that are known to need this.

in your tree?

Unless I did something wrong I also saw the failure with v5.10-rc$latest
earlier today.

... some time later ...

Argh, I checked my git reflog and the newest release I tested was
5.9-rc8.

I wonder if my patch is a simpler and more straight forward fix for the
problem however, but that might also be because I don't understand the
comment touched by 1e6114f51f9d4090390fcec2f5d67d8cc8dc4bfc without
checking the reference manual (which I didn't).

@Marian: As it's you who has to work on this i.MX25 machine, can you
maybe test if using a kernel > 5.10-rc3 (or cherry-picking
1e6114f51f9d4090390fcec2f5d67d8cc8dc4bfc) fixes the problem for you?

Tested it on 5.10-rc7 and the problem is fixed without your previous patch.

Best regards,
Marian

Best regards
Uwe