sunxi H5 DTB fix for realtek regression

Hi,

Commit bbc4d71d63549bcd003a430de18a72a742d8c91e ("net: phy: realtek: fix
rtl8211e rx/tx delay config") broke the network on the NanoPI NEO 2 board
(RTL8211E chip).

Following what was suggested by Andrew Lunn for another hardware¹, I tried
the following diff:

diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h5-nanopi-neo2.dts b/arch/arm64/boot/dts/allwinner/sun50i-h5-nanopi-neo2.dts
index 02f8e72f0cad..05486cccee1c 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-h5-nanopi-neo2.dts
+++ b/arch/arm64/boot/dts/allwinner/sun50i-h5-nanopi-neo2.dts

@@ -75,7 +75,7 @@ &emac {
        pinctrl-0 = <&emac_rgmii_pins>;
        phy-supply = <&reg_gmac_3v3>;
        phy-handle = <&ext_rgmii_phy>;
-       phy-mode = "rgmii";
+       phy-mode = "rgmii-id";
        status = "okay";
 };

...which fixed the issue. This was tested on v5.11.4 but the patch applies
cleanly on stable so far.

I'm sorry for not sending a proper patch: I unfortunately have very little
clue about what I'm doing here so it's very hard for me to elaborate a
proper commit description.

Best regards,

[1]: https://www.spinics.net/lists/netdev/msg692731.html

-- 
Clément B.

On Mon, Aug 30, 2021 at 02:52:57AM +0200, Clément Bœsch wrote:

Hi Clément

You are not too far away from a proper patch. I can either guide you,
if you want to learn, or the allwinner maintainer can probably take
your work and finish it off.

     Andrew

On Mon, Aug 30, 2021 at 03:51:25PM +0200, Andrew Lunn wrote:
[...]

quoted

I'm sorry for not sending a proper patch: I unfortunately have very little
clue about what I'm doing here so it's very hard for me to elaborate a
proper commit description.

Hi Clément

You are not too far away from a proper patch. I can either guide you,
if you want to learn, or the allwinner maintainer can probably take
your work and finish it off.

See attached patch, heavily based on other commits.

Note: running `git grep 'phy-mode\s*=\s*"rgmii"' arch` shows that it might
affect other hardware as well. I don't know how one is supposed to check
that, but I would guess at least sun50i-a64-nanopi-a64.dts is affected (a
quick internet search shows that it's using a RTL8211E¹)

The grep returns 231 occurences... A lot of other boards might have a
broken network right now.

[1]: http://nanopi.io/nanopi-a64.html

-- 
Clément B.

See attached patch, heavily based on other commits.

Looks good.

You need to add a Signed-off-by: See

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

Patches need to be in the body of the email, not attachments.

You can use scripts/get_maintainers.pl to get a list of people to send
it to. I would use To: for
Maxime Ripard [off-list ref] (maintainer:ARM/Allwinner sunXi SoC support)
Chen-Yu Tsai [off-list ref] (maintainer:ARM/Allwinner sunXi SoC support)
Jernej Skrabec [off-list ref] (reviewer:ARM/Allwinner sunXi SoC support)

and Cc: for the rest.

Note: running `git grep 'phy-mode\s*=\s*"rgmii"' arch` shows that it might
affect other hardware as well.

"rgmii" can be correct. So you need to narrow your search.

I don't know how one is supposed to check
that, but I would guess at least sun50i-a64-nanopi-a64.dts is affected (a
quick internet search shows that it's using a RTL8211E¹)

This seems reasonable. You could provide a second patch for this.

     Andrew

On Mon, Aug 30, 2021 at 05:05:28PM +0200, Andrew Lunn wrote:
[...]

You need to add a Signed-off-by: See

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin

Done.

Patches need to be in the body of the email, not attachments.

Sent through git-send-email this time (sorry about the hiccup I messed up
the first call).

You can use scripts/get_maintainers.pl to get a list of people to send
it to. I would use To: for
Maxime Ripard [off-list ref] (maintainer:ARM/Allwinner sunXi SoC support)
Chen-Yu Tsai [off-list ref] (maintainer:ARM/Allwinner sunXi SoC support)
Jernej Skrabec [off-list ref] (reviewer:ARM/Allwinner sunXi SoC support)

and Cc: for the rest.

quoted

Note: running `git grep 'phy-mode\s*=\s*"rgmii"' arch` shows that it might
affect other hardware as well.

"rgmii" can be correct. So you need to narrow your search.

Yeah I understand that, but I don't know if that can be deduced from the
code only, or if someone needs to look at the hardware specs. As said
initially, I don't have much clue about what's going on here.

quoted

I don't know how one is supposed to check
that, but I would guess at least sun50i-a64-nanopi-a64.dts is affected (a
quick internet search shows that it's using a RTL8211E¹)

This seems reasonable. You could provide a second patch for this.

I'll leave that to the other maintainers; I don't have the hardware to
test and I'm uncomfortable patching something I don't understand.

Regards,

-- 
Clément B.