linux-kernel - Re: [PATCH net-next] net: phy: aquantia: clear PMD Global Transmit Disable bit during init

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Date: Tue, 13 Feb 2024 02:52:50 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Robert Marko <robimarko@...il.com>
Cc: hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	ansuelsmth@...il.com, rmk+kernel@...linux.org.uk,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: phy: aquantia: clear PMD Global Transmit
 Disable bit during init

On Sun, Feb 11, 2024 at 07:16:41PM +0100, Robert Marko wrote:
> PMD Global Transmit Disable bit should be cleared for normal operation.
> This should be HW default, however I found that on Asus RT-AX89X that uses
> AQR113C PHY and firmware 5.4 this bit is set by default.
> 
> With this bit set the AQR cannot achieve a link with its link-partner and
> it took me multiple hours of digging through the vendor GPL source to find
> this out, so lets always clear this bit during .config_init() to avoid a
> situation like this in the future.

This all look sensible. My only question is, should we have core c45
code doing this?

[Goes and looks at 802.3]

O.K, so the Marvell PHY firmware appears to be broken. The standard
says it should have a default value of 0, i.e. the transmitter should
be enabled by default. So this is just a workaround for broken
behaviour.

> Signed-off-by: Robert Marko <robimarko@...il.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew