netdev - RE: [PATCH 2/2] net: ethernet: fsl: add phy reset after clk enable option

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Date:   Fri, 7 Jul 2017 11:08:13 +0000
From:   Andy Duan <fugang.duan@....com>
To:     Richard Leitner <richard.leitner@...data.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dev@...l1n.net" <dev@...l1n.net>, Andrew Lunn <andrew@...n.ch>
Subject: RE: [PATCH 2/2] net: ethernet: fsl: add phy reset after clk enable
 option

From: Richard Leitner <richard.leitner@...data.com> Sent: Friday, July 07, 2017 5:53 PM
>To: Andy Duan <fugang.duan@....com>; robh+dt@...nel.org;
>mark.rutland@....com
>Cc: netdev@...r.kernel.org; devicetree@...r.kernel.org; linux-
>kernel@...r.kernel.org; dev@...l1n.net; Andrew Lunn <andrew@...n.ch>
>Subject: Re: [PATCH 2/2] net: ethernet: fsl: add phy reset after clk enable
>option
>
>
>On 07/07/2017 09:03 AM, Andy Duan wrote:
>> From: Richard Leitner <richard.leitner@...data.com> Sent: Friday, July
>> 07, 2017 1:51 PM
>>>> Since it is common issue so long as using the PHY, can you move it
>>>> into smsc
>>> phy driver like in .smsc_phy_reset() function ?
>>>> And get the reset pin from phy dts node.
>>>
>>> Some more points that come into my mind:
>>>  - The smsc_phy_reset function is registered as "soft_reset". Would
>>> it be OK to use nRST in it?
>>
>> It is not reasonable.
>>
>>>  - Would it be OK to call the phy_init_hw function from within the
>>> smsc_phy_reset?
>>
>> No, phy_init_hw() already call .drv->soft_reset().
>>
>>>  - IMHO I'd have to move the reset gpio binding inside the phy node
>>> then. Isn't that a pretty big change doing that for all PHYs/FECs? Would it be
>"worth" it?
>>>
>> To make the change to be common, there have big change for phy driver.
>> Maybe somebody can give one good suggestion/solution for it.
>
>Sorry, I don't think I understood everything correctly:
>
>1. The "phy-reset-gpios" binding should go inside the phy node. This will cause
>to *change ALL FEC and PHY drivers*. Correct?
>
The "phy-reset-gpios" binding should go inside the phy node that is more reasonable.
It is better PHY core driver handle phy hw reset.

>2. Add an additonal "hard reset" function to the PHY driver which handles the
>"phy-reset-gpios". Correct?
>
Correct.

>3. Who should then trigger the "hard reset" of the PHY? phy_init_hw? The FEC?
>
>The point is that the LAN8710 is currently not always working correctly,
>therefore this small change was proposed. Should we really change all
>PHY/FECs only because of this?
>Furthermore one problem still remains: The enet_refclk is controlled by the
>FEC. How does the PHY recognize when it was disabled/enabled?
>
Your patch is workaround for the issue. As you pointed out these is a common issue.
So we hope to get a better solution to handle these in common code.

Andy