From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "Choong Yong Liang" <yong.liang.choong@linux.intel.com>,
"Rajneesh Bhardwaj" <irenic.rajneesh@gmail.com>,
"David E Box" <david.e.box@linux.intel.com>,
"Hans de Goede" <hdegoede@redhat.com>,
"Mark Gross" <markgross@kernel.org>,
"Jose Abreu" <Jose.Abreu@synopsys.com>,
"Heiner Kallweit" <hkallweit1@gmail.com>,
"David S . Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@google.com>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Marek Behún" <kabel@kernel.org>,
"Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Giuseppe Cavallaro" <peppe.cavallaro@st.com>,
"Alexandre Torgue" <alexandre.torgue@foss.st.com>,
"Jose Abreu" <joabreu@synopsys.com>,
"Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
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"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
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"Jon Hunter" <jonathanh@nvidia.com>,
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"Jochen Henneberg" <jh@henneberg-systemdesign.com>,
"David E Box" <david.e.box@intel.com>,
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"Simon Horman" <simon.horman@corigine.com>,
"Bartosz Golaszewski" <bartosz.golaszewski@linaro.org>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
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linux-arm-kernel@lists.infradead.org,
platform-driver-x86@vger.kernel.org, linux-hwmon@vger.kernel.org,
bpf@vger.kernel.org, "Voon Wei Feng" <weifeng.voon@intel.com>,
"Tan Tee Min" <tee.min.tan@linux.intel.com>,
"Michael Sit Wei Hong" <michael.wei.hong.sit@intel.com>,
"Lai Peter Jun Ann" <jun.ann.lai@intel.com>
Subject: Re: [PATCH net-next v3 0/5] TSN auto negotiation between 1G and 2.5G
Date: Thu, 21 Sep 2023 15:09:05 +0100 [thread overview]
Message-ID: <ZQxOgfw3LD5Bu2iD@shell.armlinux.org.uk> (raw)
In-Reply-To: <4caade36-d4be-4670-ac79-d9d00488293d@lunn.ch>
On Thu, Sep 21, 2023 at 03:14:59PM +0200, Andrew Lunn wrote:
> > 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.
>
> I don't think you replied to my comment.
>
> in-band is just an optimisation. It in theory allows you to avoid a
> software path, the PHY driver talking to the MAC driver about the PHY
> status. As an optimisation, it is optional. Linux has the software
> path and the MAC driver you are using basically has it implemented.
Sorry Andrew, I have to disagree. It isn't always optional - there are
PHYs out there where they won't pass data until the in-band exchange
has completed. If you try to operate out-of-band without the PHY being
told that is the case, and program the MAC/PCS end not to respond to
the in-band frames from the PHY, the PHY will report link up as normal
(since it reports the media side), but no data will flow because the
MAC facing side of the PHY hasn't completed.
The only exception are PHYs that default to in-band but have an inband
bypass mode also enabled to cover the case where the MAC/PCS doesn't
respond to the inband messages.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
next prev parent reply other threads:[~2023-09-21 18:11 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-21 12:19 [PATCH net-next v3 0/5] TSN auto negotiation between 1G and 2.5G Choong Yong Liang
2023-09-21 12:19 ` [PATCH net-next v3 1/5] arch: x86: Add IPC mailbox accessor function and add SoC register access Choong Yong Liang
2023-09-22 9:45 ` Simon Horman
2023-09-21 12:19 ` [PATCH net-next v3 2/5] net: pcs: xpcs: combine C37 SGMII AN and 2500BASEX for Intel mGbE controller Choong Yong Liang
2023-09-21 13:06 ` Russell King (Oracle)
2023-09-26 10:51 ` Serge Semin
2024-01-29 13:15 ` Choong Yong Liang
2023-09-21 12:19 ` [PATCH net-next v3 3/5] net: phy: update in-band AN mode when changing interface by PHY driver Choong Yong Liang
2023-09-21 14:04 ` Russell King (Oracle)
2024-01-29 13:18 ` Choong Yong Liang
2023-09-21 12:19 ` [PATCH net-next v3 4/5] net: stmmac: enable Intel mGbE 1G/2.5G auto-negotiation support Choong Yong Liang
2023-09-21 13:28 ` Russell King (Oracle)
2023-09-26 10:55 ` Serge Semin
2024-01-29 13:19 ` Choong Yong Liang
2024-01-29 13:41 ` Andrew Lunn
2024-02-02 3:07 ` Choong Yong Liang
2023-09-21 12:19 ` [PATCH net-next v3 5/5] stmmac: intel: Add 1G/2.5G auto-negotiation support for ADL-N Choong Yong Liang
2023-09-21 13:14 ` [PATCH net-next v3 0/5] TSN auto negotiation between 1G and 2.5G Andrew Lunn
2023-09-21 14:09 ` Russell King (Oracle) [this message]
2024-01-29 13:13 ` Choong Yong Liang
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