Re: [linux-sunxi] [PATCH 02/10] ARM: dts: sun6i: a31-hummingbird: Enable RGMII RX/TX delay on Ethernet PHY

Hi,

On Sat, 24 Oct 2020 at 20:39, Icenowy Zheng [off-list ref] wrote:

于 2020年10月25日 GMT+08:00 上午2:30:35, "Jernej Škrabec" [off-list ref] 写到:

quoted

Dne sobota, 24. oktober 2020 ob 19:51:06 CEST je Icenowy Zheng
napisal(a):

quoted

在 2020-10-25星期日的 00:25 +0800，Chen-Yu Tsai写道：

quoted

From: Chen-Yu Tsai <redacted>

The Ethernet PHY on the A31 Hummingbird has the RX and TX delays
enabled on the PHY, using pull-ups on the RXDLY and TXDLY pins.

Fix the phy-mode description to correct reflect this so that the
implementation doesn't reconfigure the delays incorrectly. This
happened with commit bbc4d71d6354 ("net: phy: realtek: fix rtl8211e
rx/tx delay config").

Personally I think they should revert this commit, and consider other
solution.

This commit breaks everything.

Previously broken driver allowed inproper DT to work, so you have to
fix
everything eventually.

There is no "improper DT" if it's already shipped, DT should suffer driver
change, not changed to match driver.

I think at least Fedora tends to ship a DT with a system image that will
not get updated when kernel gets updated.

I think we are missing a phy-mode saying use RGMII but don't change
the delay set by the hardware.
Or maybe introduce a phy-mode='rgmii-noid' to explicitly disable the
RX/TD delay using software bits
and use phy-mode='rgmii' to keep the delay set by the hardware.

Clement

quoted

Plus side, there is no need to have hack for Pine64 Plus ethernet
anymore.

Best regards,
Jernej

quoted

(Although the patch on individual DT patches are technically correct)

quoted

Fixes: c220aec2bb79 ("ARM: dts: sun6i: Add Merrii A31 Hummingbird
support")
Signed-off-by: Chen-Yu Tsai <redacted>
---

 arch/arm/boot/dts/sun6i-a31-hummingbird.dts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/sun6i-a31-hummingbird.dts

b/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
index 049e6ab3cf56..73de34ae37fd 100644

--- a/arch/arm/boot/dts/sun6i-a31-hummingbird.dts
+++ b/arch/arm/boot/dts/sun6i-a31-hummingbird.dts

@@ -154,7 +154,7 @@ &gmac {

   pinctrl-names = "default";
   pinctrl-0 = <&gmac_rgmii_pins>;
   phy-handle = <&phy1>;

-  phy-mode = "rgmii";
+  phy-mode = "rgmii-id";

   status = "okay";

 };

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