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

[Maxime Chevallier <maxime.chevallier@bootlin.com>]

Hi,

On 7/27/26 04:10, Gavin Gao 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.

I have a feeling this is using the common clock framework backwards. The
MAC in this case is a clock provider yet it uses the consumer API.

Shouldn't the MAC instead register a new clock, as a provider, for the ref
out ? The PHY device would then need to get/prepare/enable that clock.

I know we don't have a lot of clock providers in drivers/net/ethernet, but
I think we should have more...

Maxime

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