Re: [PATCH net-next v2 0/5] TSN auto negotiation between 1G and 2.5G

From: Choong Yong Liang <yong.liang.choong@linux.intel.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Rajneesh Bhardwaj" <irenic.rajneesh@gmail.com>,
	"David E Box" <david.e.box@linux.intel.com>,
	"Hans de Goede" <hdegoede@redhat.com>,
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	"Paolo Abeni" <pabeni@redhat.com>,
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	bpf@vger.kernel.org, "Voon Wei Feng" <weifeng.voon@intel.com>,
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	"Michael Sit Wei Hong" <michael.wei.hong.sit@intel.com>,
	"Lai Peter Jun Ann" <jun.ann.lai@intel.com>
Subject: Re: [PATCH net-next v2 0/5] TSN auto negotiation between 1G and 2.5G
Date: Thu, 10 Aug 2023 17:52:10 +0800	[thread overview]
Message-ID: <5e113258-7cb4-e503-5009-e46cd3aa5bee@linux.intel.com> (raw)
In-Reply-To: <5bd05ba2-fd88-4e5c-baed-9971ff917484@lunn.ch>

On 4/8/2023 8:04 pm, Andrew Lunn wrote:
> On Fri, Aug 04, 2023 at 04:45:22PM +0800, Choong Yong Liang wrote:
>> Intel platforms’ integrated Gigabit Ethernet controllers support
>> 2.5Gbps mode statically using BIOS programming. In the current
>> implementation, the BIOS menu provides an option to select between
>> 10/100/1000Mbps and 2.5Gbps modes. Based on the selection, the BIOS
>> programs the Phase Lock Loop (PLL) registers. The BIOS also read the
>> TSN lane registers from Flexible I/O Adapter (FIA) block and provided
>> 10/100/1000Mbps/2.5Gbps information to the stmmac driver. But
>> auto-negotiation between 10/100/1000Mbps and 2.5Gbps is not allowed.
>> The new proposal is to support auto-negotiation between 10/100/1000Mbps
>> and 2.5Gbps . Auto-negotiation between 10, 100, 1000Mbps will use
>> in-band auto negotiation. Auto-negotiation between 10/100/1000Mbps and
>> 2.5Gbps will work as the following proposed flow, the stmmac driver reads
>> the PHY link status registers then identifies the negotiated speed.
>> Based on the speed stmmac driver will identify TSN lane registers from
>> FIA then send IPC command to the Power Management controller (PMC)
>> through PMC driver/API. PMC will act as a proxy to programs the
>> PLL registers.
> 
> Have you considered using out of band for all link modes? You might
> end up with a cleaner architecture, and not need any phylink/phylib
> hacks.
> 
> 	Andrew
Hi Andrew,

Thank you for your feedback.
I will study the feasibility of the out-of-band (OOB) approach.