Re: [PATCH net-next 0/3] net: stmmac: dwmac-rk: add RK3576 GMAC 25M refout support

On 7/27/2026 3:14 PM, Alexey Charkov wrote:

Hi Gavin,

On Mon, Jul 27, 2026 at 6:10 AM Gavin Gao [off-list ref] wrote:

quoted

Hi,

Some Rockchip GMAC instances can provide a 25 MHz reference clock output
for an external RGMII PHY. Boards already describe the MAC clock direction
with clock_in_out = "output", but the dwmac-rk driver does not currently
request or enable the corresponding 25 MHz reference output clock.

On RK3576, this means the REFCLKO25M_GMACx_OUT clock may be disabled by
the common clock framework as unused, even though the board expects the
GMAC block to provide the PHY reference clock.

This series adds an optional "clk_mac_25m_refout" clock name to the
Rockchip DWMAC binding, wires it up for RK3576 GMAC0/GMAC1, and enables
it from the dwmac-rk driver when the MAC is configured for RGMII output
clock mode.

The clock remains optional, so existing device trees and SoCs are not
affected.

Tested on a PicoCOM RK3576 ACP board with a Motorcomm YT8521 PHY.
The GMAC 25 MHz reference clock output remains active and Ethernet works.

Gavin Gao (3):
  dt-bindings: net: rockchip-dwmac: Add 25M refout clock
  arm64: dts: rockchip: Add RK3576 GMAC 25M refout clocks
  net: stmmac: dwmac-rk: Enable RGMII 25M refout clock

 .../bindings/net/rockchip-dwmac.yaml          |  1 +
 arch/arm64/boot/dts/rockchip/rk3576.dtsi      |  8 ++---
 .../net/ethernet/stmicro/stmmac/dwmac-rk.c    | 33 ++++++++++++++++++-
 3 files changed, 37 insertions(+), 5 deletions(-)

Can you please try something like this [1] instead?

[1] https://lore.kernel.org/linux-rockchip/20260719034555.3623003-1-gahing@gahingwoo.com/ (local)

The GMAC on RK3576 neither produces nor consumes the clock. CRU is the
producer, and PHY is the consumer. So the GMAC driver shouldn't be the
one to enable it, nor should the dwmac binding have anything to do
with it.

Have a look at how other boards already upstream handle this. For
example, the RK3576 EVB1 uses a similar arrangement but with a
different PHY.

Yep, we had a similar fix, but it was rejected. Please see how RK3576 EVB1 does it:

https://lore.kernel.org/all/20250910-rk3576-evb-network-v1-1-68ed4df272a2@collabora.com/ (local)


-- 
Best, 
Chaoyi