netdev - Re: [PATCH v3] net: mdio: mux-meson-gxl: set reversed bit when using internal phy

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Message-ID: <CACdvmAhcBmoDNyuu0npZzyExfhyLKdyPw9HvHvV+OdADxEfJJQ@mail.gmail.com>
Date: Mon, 28 Apr 2025 20:44:14 -0400
From: Da Xue <da@...sconfused.com>
To: Simon Horman <horms@...nel.org>
Cc: Da Xue <da@...re.computer>, Andrew Lunn <andrew@...n.ch>, 
	Neil Armstrong <neil.armstrong@...aro.org>, 
	Martin Blumenstingl <martin.blumenstingl@...glemail.com>, Kevin Hilman <khilman@...libre.com>, 
	Russell King <linux@...linux.org.uk>, stable@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org, 
	Jerome Brunet <jbrunet@...libre.com>, Jakub Kicinski <kuba@...nel.org>, 
	linux-amlogic@...ts.infradead.org, Paolo Abeni <pabeni@...hat.com>, 
	"David S. Miller" <davem@...emloft.net>, linux-arm-kernel@...ts.infradead.org, 
	Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH v3] net: mdio: mux-meson-gxl: set reversed bit when using
 internal phy

On Mon, Apr 28, 2025 at 2:13 PM Simon Horman <horms@...nel.org> wrote:
>
> On Fri, Apr 25, 2025 at 03:20:09PM -0400, Da Xue wrote:
> > This bit is necessary to receive packets from the internal PHY.
> > Without this bit set, no activity occurs on the interface.
> >
> > Normally u-boot sets this bit, but if u-boot is compiled without
> > net support, the interface will be up but without any activity.
> >
> > The vendor SDK sets this bit along with the PHY_ID bits.
>
> I'd like to clarify that:
> Without this patch the writel the patch is modifying will clear the PHY_ID bit.
> But despite that the system works if at some point (uboot) set the PHY_ID bit?

Correct. If this is set once, it will work until the IP is powered
down or reset.
If u-boot does not set it, Linux will not set it and the IP will not work.
If u-boot does set it, the IP will not work after suspend-resume since
the IP is reset.
Thus, we need to set it on the Linux side when bringing up the interface.

>
> >
> > Fixes: 9a24e1ff4326 ("net: mdio: add amlogic gxl mdio mux support");
>
> I don't think you need to resend because of this,
> but the correct syntax is as follows. (No trailing ';'.)

Great and thanks! I just set up git send-email so I'm a little rough
around the edges.

>
> Fixes: 9a24e1ff4326 ("net: mdio: add amlogic gxl mdio mux support")
>
> > Signed-off-by: Da Xue <da@...re.computer>
> > ---
> > Changes since v2:
> > * Rename REG2_RESERVED_28 to REG2_REVERSED
> >
> > Link to v2:
> > https://patchwork.kernel.org/project/linux-amlogic/patch/20250331074420.3443748-1-christianshewitt@gmail.com/
>
> ...
>
> _______________________________________________
> linux-amlogic mailing list
> linux-amlogic@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-amlogic

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