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From: Stefan Chulski <stefanc@marvell.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "kuba@kernel.org" <kuba@kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"thomas.petazzoni@bootlin.com" <thomas.petazzoni@bootlin.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	Nadav Haklai <nadavh@marvell.com>,
	Yan Markman <ymarkman@marvell.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux@armlinux.org.uk" <linux@armlinux.org.uk>,
	"mw@semihalf.com" <mw@semihalf.com>,
	"rmk+kernel@armlinux.org.uk" <rmk+kernel@armlinux.org.uk>,
	"atenart@kernel.org" <atenart@kernel.org>,
	"rabeeh@solid-run.com" <rabeeh@solid-run.com>
Subject: RE: [EXT] Re: [V2 net-next] net: mvpp2: Add reserved port private flag configuration
Date: Mon, 22 Mar 2021 15:59:43 +0000	[thread overview]
Message-ID: <CO6PR18MB3873543426EC122F1C53DC40B0659@CO6PR18MB3873.namprd18.prod.outlook.com> (raw)
In-Reply-To: <YFO9ug0gZp8viEHn@lunn.ch>


> > 2. CM3 code has very small footprint requirement, we cannot 
> > implement the complete Serdes and PHY infrastructure that kernel 
> > provides as part of CM3 application. Therefore I would like to 
> > continue relying on kernel configuration for that.
> 
> How can that work? How does Linux know when CM3 has up'ed the 
> interface?

CM3 won't use this interface till ethtool priv flag was set, it can be done by communication over CM3 SRAM memory.

> How does CM3 know the status of the link?

CM3 has access to MAC registers and can read port status bit.

> How does CM3 set its
> flow control depending on what auto-neg determines, etc?

Same as PPv2 Packet Processor RX and TX flow don't really care about auto-neg, flow control, etc.
CM3 can ignore it, all this stuff handled in MAC layer. CM3 just polling RX descriptor ring and using TX ring for transmit. 

> 
> > 3. In some cases we need to dynamically switch the port "user"
> > between CM3 and kernel. So I would like to preserve this 
> > functionality.
> 
> And how do you synchronize between Linux and CM3 so you know how is 
> using it and who cannot use it?
> 
>       Andrew

I can add CM3 SRAM update into ethtool priv flag callback, so CM3 won't use port till it was reserved to CM3.

Stefan.

  reply	other threads:[~2021-03-22 16:00 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-11 16:43 [V2 net-next] net: mvpp2: Add reserved port private flag configuration stefanc
2021-03-11 16:59 ` Andrew Lunn
2021-03-16 15:28   ` [EXT] " Stefan Chulski
2021-03-16 15:41     ` Russell King - ARM Linux admin
2021-03-16 16:51       ` Stefan Chulski
2021-03-18 20:53     ` Andrew Lunn
2021-03-22 15:59       ` Stefan Chulski [this message]
2021-03-22 16:28         ` Andrew Lunn
2021-03-22 18:24           ` Stefan Chulski
2021-03-11 20:33 ` Jakub Kicinski

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