Re: [PATCH] arm64: dts: allwinner: Orange Pi One Plus PHY support

[Anne Macedo]

On Tue, Dec 12, 2023 at 04:22:00PM +0000, Andre Przywara wrote:
> On Tue, 12 Dec 2023 12:28:30 +0000
> Anne Macedo <retpolanne@xxxxxxxxxx> wrote:
> 
> Hi Anne,
> 
> > Adds compatible values to mdio subnodes for Ethernet PHY representing
> > Realtek 8211 PHY to Orange Pi One Plus.
> 
> So can you state why this would be needed? This is the RTL8211 ID,

Apologies, I completely forgot to include some context. 

> right? Which should be autodetected via MDIO. Looking back in my inbox
> you proposed this change before, for U-Boot, specifically, but I fail to
> find a solution or explanation what really happens here. Two Renesas .dts
> files have the same compatible, and the commit message talks about the
> reset line there, is this related?
> 
> So can you please give some more background and explanation? That would be
> part of a good commit message anyway ("why", not "what").

Should I resend the commit with a more meaningful explanation? The
context is the following:

currently, ethernet doesn't seem to work on both u-boot and Linux on the
Orange Pi One Plus board. 

On the kernel, this error shows up:

Configuring network interfaces... [    5.992589] dwmac-sun8i 5020000.ethernet eth0: Register MEM_TYPE_PAGE_POOL RxQ-0
[    6.000823] dwmac-sun8i 5020000.ethernet eth0: __stmmac_open: Cannot attach to PHY (error: -19)

After applying this fix, the PHY gets attached: 

Configuring network interfaces... [    6.060020] dwmac-sun8i 5020000.ethernet eth0: Register MEM_TYPE_PAGE_POOL RxQ-0
[    6.069460] dwmac-sun8i 5020000.ethernet eth0: PHY [stmmac-0:01] driver [RTL8211E Gigabit Ethernet] (irq=POLL)

The previous compatible list that had ethernet-phy-ieee802.3-c22 fails
to find a PHY, so this patch includes the correct PHY ID with the
RTL8211 ID. 

The behaviour is described on [1]. U-boot fails completely if the
correct PHY ID is not correct, and in order to fix U-boot we need to fix
the upstream dts [2].

[1] https://elixir.bootlin.com/linux/v4.14/source/Documentation/devicetree/bindings/net/phy.txt#L20
[2] https://elixir.bootlin.com/u-boot/latest/source/drivers/core/ofnode.c#L1258

> 
> Cheers,
> Andre
> 
> > Signed-off-by: Anne Macedo <retpolanne@xxxxxxxxxx>
> > ---
> >  arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts
> > index 29a081e72..7248ab72f 100644
> > --- a/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts
> > +++ b/arch/arm64/boot/dts/allwinner/sun50i-h6-orangepi-one-plus.dts
> > @@ -37,7 +37,8 @@ &emac {
> >  
> >  &mdio {
> >  	ext_rgmii_phy: ethernet-phy@1 {
> > -		compatible = "ethernet-phy-ieee802.3-c22";
> > +		compatible = "ethernet-phy-id001c.c915",
> > +			     "ethernet-phy-ieee802.3-c22";
> >  		reg = <1>;
> >  	};
> >  };
> 

Regards, Anne