linux-kernel - Re: [PATCH v2] net: phy: dp83867: perform soft reset and retain established link

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Date:   Fri, 11 Jun 2021 12:05:41 -0500
From:   "Bajjuri, Praneeth" <praneeth@...com>
To:     Johannes Pointner <h4nn35.work@...il.com>,
        Geet Modi <geet.modi@...com>, Andrew Lunn <andrew@...n.ch>
CC:     <netdev@...r.kernel.org>, "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] net: phy: dp83867: perform soft reset and retain
 established link

Hannes,

On 6/10/2021 12:53 AM, Johannes Pointner wrote:
> Hello,
> 
> On Thu, Jun 10, 2021 at 6:10 AM Andrew Lunn <andrew@...n.ch> wrote:
>>
>> On Wed, Jun 09, 2021 at 07:43:42PM -0500, praneeth@...com wrote:
>>> From: Praneeth Bajjuri <praneeth@...com>
>>>
>>> Current logic is performing hard reset and causing the programmed
>>> registers to be wiped out.
>>>
>>> as per datasheet: https://www.ti.com/lit/ds/symlink/dp83867cr.pdf
>>> 8.6.26 Control Register (CTRL)
>>>
>>> do SW_RESTART to perform a reset not including the registers,
>>> If performed when link is already present,
>>> it will drop the link and trigger re-auto negotiation.
>>>
>>> Signed-off-by: Praneeth Bajjuri <praneeth@...com>
>>> Signed-off-by: Geet Modi <geet.modi@...com>
>>
>> Reviewed-by: Andrew Lunn <andrew@...n.ch>
>>
>>      Andrew
> 
> I reported a few days ago an issue with the DP83822 which I think is
> caused by a similar change.
> https://lore.kernel.org/netdev/CAHvQdo2yzJC89K74c_CZFjPydDQ5i22w36XPR5tKVv_W8a2vcg@mail.gmail.com/
> In my case I can't get an link after this change, reverting it fixes
> the problem for me.

Are you saying that instead of reset if sw_restart is done as per this 
patch, there is no issue?

> 
> Hannes
>