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Subject[PATCH 4.19 415/639] arm64: dts: renesas: ebisu: Remove renesas, no-ether-link property
Date
From: Takeshi Kihara <takeshi.kihara.df@renesas.com>

[ Upstream commit 90d4fa39d028f2e46c57c3d0e1b759e5287d98b7 ]

It is incorrect to specify the no-ether-link property for the AVB device on
the Ebisu board. This is because the property should only be used when a
board does not provide a proper AVB_LINK signal. However, the Ebisu board
does provide this signal.

As per 87c059e9c39d ("arm64: dts: renesas: salvator-x: Remove renesas,
no-ether-link property") this fixes a bug:

Steps to reproduce:
- start AVB TX stream (Using aplay via MSE),
- disconnect+reconnect the eth cable,
- after a reconnection the eth connection goes iteratively up/down
without user interaction,
- this may heal after some seconds or even stay for minutes.

As the documentation specifies, the "renesas,no-ether-link" option
should be used when a board does not provide a proper AVB_LINK signal.
There is no need for this option enabled on RCAR H3/M3 Salvator-X/XS
and ULCB starter kits since the AVB_LINK is correctly handled by HW.

Choosing to keep or remove the "renesas,no-ether-link" option will have
impact on the code flow in the following ways:
- keeping this option enabled may lead to unexpected behavior since the
RX & TX are enabled/disabled directly from adjust_link function
without any HW interrogation,
- removing this option, the RX & TX will only be enabled/disabled after
HW interrogation. The HW check is made through the LMON pin in PSR
register which specifies AVB_LINK signal value (0 - at low level;
1 - at high level).

In conclusion, the present change is also a safety improvement because
it removes the "renesas,no-ether-link" option leading to a proper way
of detecting the link state based on HW interrogation and not on
software heuristic.

Fixes: 8441ef643d7d ("arm64: dts: renesas: r8a77990: ebisu: Enable EthernetAVB")
Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
[simon: updated changelog]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts | 1 -
1 file changed, 1 deletion(-)

diff --git a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
index 2bc3a4884b003..470c2a35a5aff 100644
--- a/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
+++ b/arch/arm64/boot/dts/renesas/r8a77990-ebisu.dts
@@ -33,7 +33,6 @@
&avb {
pinctrl-0 = <&avb_pins>;
pinctrl-names = "default";
- renesas,no-ether-link;
phy-handle = <&phy0>;
phy-mode = "rgmii-txid";
status = "okay";
--
2.20.1


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