All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Siddharth Vadapalli <s-vadapalli@ti.com>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, robh+dt@kernel.org,
	krzysztof.kozlowski@linaro.org,
	krzysztof.kozlowski+dt@linaro.org, vladimir.oltean@nxp.com,
	grygorii.strashko@ti.com, vigneshr@ti.com, nsekhar@ti.com,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kishon@ti.com
Subject: Re: [PATCH 5/8] net: ethernet: ti: am65-cpsw: Add support for fixed-link configuration
Date: Wed, 14 Sep 2022 17:09:30 +0100	[thread overview]
Message-ID: <YyH8us424n3dyLYT@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220914095053.189851-6-s-vadapalli@ti.com>

On Wed, Sep 14, 2022 at 03:20:50PM +0530, Siddharth Vadapalli wrote:
> Check for fixed-link in am65_cpsw_nuss_mac_config() using struct
> am65_cpsw_slave_data's phy_node property to obtain fwnode. Since
> am65_cpsw_nuss_mac_link_up() is not invoked in fixed-link mode, perform
> the relevant operations in am65_cpsw_nuss_mac_config() itself.

Further to my other comments, you also fail to explain that, when in
fixed-link SGMII mode, you _emulate_ being a PHY - which I deduce
since you are sending the duplex setting and speed settings via the
SGMII control word. Also, as SGMII was invented for a PHY to be able
to communicate the media negotiation resolution to the MAC, SGMII
defines that the PHY fills in the speed and duplex information in
the control word to pass it to the MAC, and the MAC acknowledges this
information. There is no need (and SGMII doesn't permit) the MAC to
advertise what it's doing.

Maybe this needs to be explained in the commit message?

This doesn't have any bearing on the other comments I've made.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

WARNING: multiple messages have this Message-ID (diff)
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Siddharth Vadapalli <s-vadapalli@ti.com>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
	pabeni@redhat.com, robh+dt@kernel.org,
	krzysztof.kozlowski@linaro.org,
	krzysztof.kozlowski+dt@linaro.org, vladimir.oltean@nxp.com,
	grygorii.strashko@ti.com, vigneshr@ti.com, nsekhar@ti.com,
	netdev@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kishon@ti.com
Subject: Re: [PATCH 5/8] net: ethernet: ti: am65-cpsw: Add support for fixed-link configuration
Date: Wed, 14 Sep 2022 17:09:30 +0100	[thread overview]
Message-ID: <YyH8us424n3dyLYT@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220914095053.189851-6-s-vadapalli@ti.com>

On Wed, Sep 14, 2022 at 03:20:50PM +0530, Siddharth Vadapalli wrote:
> Check for fixed-link in am65_cpsw_nuss_mac_config() using struct
> am65_cpsw_slave_data's phy_node property to obtain fwnode. Since
> am65_cpsw_nuss_mac_link_up() is not invoked in fixed-link mode, perform
> the relevant operations in am65_cpsw_nuss_mac_config() itself.

Further to my other comments, you also fail to explain that, when in
fixed-link SGMII mode, you _emulate_ being a PHY - which I deduce
since you are sending the duplex setting and speed settings via the
SGMII control word. Also, as SGMII was invented for a PHY to be able
to communicate the media negotiation resolution to the MAC, SGMII
defines that the PHY fills in the speed and duplex information in
the control word to pass it to the MAC, and the MAC acknowledges this
information. There is no need (and SGMII doesn't permit) the MAC to
advertise what it's doing.

Maybe this needs to be explained in the commit message?

This doesn't have any bearing on the other comments I've made.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-09-14 16:09 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-14  9:50 [PATCH 0/8] Add support for J721e CPSW9G and SGMII mode Siddharth Vadapalli
2022-09-14  9:50 ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 1/8] dt-bindings: net: ti: k3-am654-cpsw-nuss: Update bindings for J721e CPSW9G Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 16:20   ` Rob Herring
2022-09-14 16:20     ` Rob Herring
2022-09-15  7:28     ` Siddharth Vadapalli
2022-09-15  7:28       ` Siddharth Vadapalli
2022-09-14 16:23   ` Rob Herring
2022-09-14 16:23     ` Rob Herring
2022-09-15  7:40     ` Siddharth Vadapalli
2022-09-15  7:40       ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 2/8] net: ethernet: ti: am65-cpsw: Add support for SERDES configuration Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 15:37   ` Russell King (Oracle)
2022-09-14 15:37     ` Russell King (Oracle)
2022-09-15  8:36     ` Siddharth Vadapalli
2022-09-15  8:36       ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 3/8] net: ethernet: ti: am65-cpsw: Add mac control function Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 15:53   ` Russell King (Oracle)
2022-09-14 15:53     ` Russell King (Oracle)
2022-09-14  9:50 ` [PATCH 4/8] net: ethernet: ti: am65-cpsw: Add mac enable link function Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 15:54   ` Russell King (Oracle)
2022-09-14 15:54     ` Russell King (Oracle)
2022-09-14  9:50 ` [PATCH 5/8] net: ethernet: ti: am65-cpsw: Add support for fixed-link configuration Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 15:41   ` Russell King (Oracle)
2022-09-14 15:41     ` Russell King (Oracle)
2022-09-15  8:59     ` Siddharth Vadapalli
2022-09-15  8:59       ` Siddharth Vadapalli
2022-09-14 16:09   ` Russell King (Oracle) [this message]
2022-09-14 16:09     ` Russell King (Oracle)
2022-09-15  9:28     ` Siddharth Vadapalli
2022-09-15  9:28       ` Siddharth Vadapalli
2022-09-15 10:07       ` Russell King (Oracle)
2022-09-15 10:07         ` Russell King (Oracle)
2022-09-16  4:54         ` Siddharth Vadapalli
2022-09-16  4:54           ` Siddharth Vadapalli
2022-09-16  7:20           ` Russell King (Oracle)
2022-09-16  7:20             ` Russell King (Oracle)
2022-09-16  9:03             ` Siddharth Vadapalli
2022-09-16  9:03               ` Siddharth Vadapalli
2022-09-16  9:14               ` Russell King (Oracle)
2022-09-16  9:14                 ` Russell King (Oracle)
2022-09-16  9:55                 ` Siddharth Vadapalli
2022-09-16  9:55                   ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 6/8] net: ethernet: ti: am65-cpsw: Add support for SGMII mode for J7200 CPSW5G Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14 15:44   ` Russell King (Oracle)
2022-09-14 15:44     ` Russell King (Oracle)
2022-09-15  9:35     ` Siddharth Vadapalli
2022-09-15  9:35       ` Siddharth Vadapalli
2022-09-14 16:04   ` Russell King (Oracle)
2022-09-14 16:04     ` Russell King (Oracle)
2022-09-15  9:40     ` Siddharth Vadapalli
2022-09-15  9:40       ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 7/8] net: ethernet: ti: am65-cpsw: Add support for J721e CPSW9G Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-14  9:50 ` [PATCH 8/8] net: ethernet: ti: am65-cpsw: Enable SGMII mode " Siddharth Vadapalli
2022-09-14  9:50   ` Siddharth Vadapalli
2022-09-16  9:57 ` [PATCH 0/8] Add support for J721e CPSW9G and SGMII mode Krzysztof Kozlowski
2022-09-16  9:57   ` Krzysztof Kozlowski
2022-09-16 10:07   ` Siddharth Vadapalli
2022-09-16 10:07     ` Siddharth Vadapalli

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=YyH8us424n3dyLYT@shell.armlinux.org.uk \
    --to=linux@armlinux.org.uk \
    --cc=davem@davemloft.net \
    --cc=devicetree@vger.kernel.org \
    --cc=edumazet@google.com \
    --cc=grygorii.strashko@ti.com \
    --cc=kishon@ti.com \
    --cc=krzysztof.kozlowski+dt@linaro.org \
    --cc=krzysztof.kozlowski@linaro.org \
    --cc=kuba@kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=nsekhar@ti.com \
    --cc=pabeni@redhat.com \
    --cc=robh+dt@kernel.org \
    --cc=s-vadapalli@ti.com \
    --cc=vigneshr@ti.com \
    --cc=vladimir.oltean@nxp.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.