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

[Alexey Charkov]

Hi Gavin,

On Mon, Jul 27, 2026 at 6:10 AM Gavin Gao <attinagaoxu@xxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxxxx/

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.

Best regards,
Alexey