netdev - Re: [PATCH 0/2] at803x: don't power-down SGMII link

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Date:   Tue, 25 Oct 2016 12:31:21 -0500
From:   Timur Tabi <timur@...eaurora.org>
To:     Zefir Kurtisi <zefir.kurtisi@...atec.com>, netdev@...r.kernel.org
Cc:     andrew@...n.ch, f.fainelli@...il.com
Subject: Re: [PATCH 0/2] at803x: don't power-down SGMII link

Zefir Kurtisi wrote:
> In a device where the ar8031 operates in SGMII mode, we
> observed that after a suspend-resume cycle in very rare
> cases the copper side autonegotiation secceeds but the
> SGMII side fails to come up.
>
> As a work-around, a patch was provided that on suspend and
> resume powers the SGMII link down and up along with the
> copper side. This fixed the observed failure, but
> introduced a regression Timur Tabi observed: once the SGMII
> is powered down, the PHY is inaccessible by the CPU and
> with that e.g. can't be re-initialized after suspend.
>
> Since the original issue could not be reproduced by others,
> this series provides an alternative handling:
> * the first patch reverts the prvious fix that powers down
>    SGMII
> * the second patch adds double-checking for the observed
>    failure condition
>
> Zefir Kurtisi (2):
>    Revert "at803x: fix suspend/resume for SGMII link"
>    at803x: double check SGMII side autoneg

Tested-by: Timur Tabi <timur@...eaurora.org>

With these patches, the problem I was seeing no longer occurs, and the 
new code does not appear to break anything.  As before, I still have 
never seen the original problem, but this patchset seems to work for 
both of us.

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