netdev - Re: [PATCH net-next v3 2/2] net: ethernet: Add driver for Sunplus SP7021

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Message-ID: <YajEbXtBwlDL4gOL@lunn.ch>
Date:   Thu, 2 Dec 2021 14:04:45 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Wells Lu 呂芳騰 <wells.lu@...plus.com>
Cc:     Wells Lu <wellslutw@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "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>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        Vincent Shih 施錕鴻 
        <vincent.shih@...plus.com>
Subject: Re: [PATCH net-next v3 2/2] net: ethernet: Add driver for Sunplus
 SP7021

> I printed out the value of 'supported' and 'advertising'.
> 'supported' shows PHY device supports Pause and AsymPause (0x62cf).
> But 'advertising' shows PHY device does not support Pause or AsymPause (0x02cf).
> Is this correct?
> 
> How to let link partner know local node supports 
> Pause & AsymPause (flow control)?
>

'supported' indicates that the PHY can do. It has the ability to
advertise pause. But we don't automatically copy those bits into
'advertising' because we don't know if the MAC actually supports
pause/asym pause.

The MAC driver needs to call phy_support_sym_pause() or
phy_support_asym_pause() to let phylib know what it can do. phylib
will then add the appropriate bits to 'advertising'.

> Will mii_read() and mii_write() be called in interrupt context?

No. Only thread context, because it uses a mutex to prevent multiple
accesses at the same time.

	 Andrew