[RFC PATCH v2 0/7] Add ethernet support for the Amlogic T7

[Lucas Tanure]

The T7 pairs a Synopsys gigabit MAC with the same glue registers the
G12A has, but nothing described it. This adds the binding, the driver
support and the device tree nodes, and enables the port on the Khadas
VIM4.

Unlike the G12A, the controller reaches DRAM through a pipeline stage
with a gate of its own, sys_ampipe_eth. Nothing else claims it, so
clk_disable_unused switches it off and transfers stop.

v2 changes the RGMII delays, after review. phy-mode describes the
board, not which chip adds the delay, so this board is rgmii-id.
dwmac-meson8b did the opposite, and ignored the *-internal-delay-ps
properties. Patch 1 fixes that. The VIM4 needs it because the RTL8211F
transmit delay does not work here. Boards declaring neither property
are unaffected.

Tested on next-20261002 with "clk: meson: t7: keep the memory fabric
clocks running" (clk-meson-next) on top, needed before any DMA on this
SoC works: 935Mbit/s both ways for 30s, no CRC error in 2.59M frames.

Overlaps with Xianwei Zhao's "[PATCH v2 0/3] t7: add some nodes for
Amlogc t7.", which defines amlogic,t7-dwmac with the axg fallback and
three clocks. My board reports Synopsys ID 0x51, DWMAC_CORE_5_10, and
does not survive the clock sweep without the pipeline gate. I will drop
or rebase whatever overlaps once we agree. Patch 2 is the oneOf rewrite
Conor asked for there.

Changes since v1:
 - new patch 1: honour tx-internal-delay-ps and rx-internal-delay-ps in
   the rgmii-*id modes, and pass the PHY whatever delay is left over
 - vim4: phy-mode rgmii -> rgmii-id, and amlogic,tx-delay-ns plus
   rx-internal-delay-ps replaced by tx-internal-delay-ps = <2000>.
   Neil's Reviewed-by dropped from this one, the change is not cosmetic

Lucas Tanure (7):
  net: stmmac: dwmac-meson8b: let the controller apply the RGMII delays
  dt-bindings: net: amlogic,meson-dwmac: list the compatible
    combinations
  dt-bindings: net: amlogic,meson-dwmac: add amlogic,t7-dwmac
  net: stmmac: dwmac-meson8b: add support for the Amlogic T7
  arm64: dts: amlogic: t7: add the ethernet pinctrl nodes
  arm64: dts: amlogic: t7: add the ethernet controller
  arm64: dts: amlogic: t7: khadas-vim4: enable the ethernet port

 .../bindings/net/amlogic,meson-dwmac.yaml     | 77 ++++++++++++----
 .../amlogic/amlogic-t7-a311d2-khadas-vim4.dts | 22 +++++
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi   | 87 +++++++++++++++++++
 .../ethernet/stmicro/stmmac/dwmac-meson8b.c   | 65 +++++++++++++-
 4 files changed, 234 insertions(+), 17 deletions(-)

-- 
2.56.0