[PATCH net-next] net: stmmac: dwmac-rk: enable the reference clock for output mode

[PATCH net-next] net: stmmac: dwmac-rk: enable the reference clock for output mode

[Jiaxing Hu]

rk_gmac_clk_init() only requests the refout clock group for RMII. The
ArmSoM CM5 has an on-module YT8531 RGMII PHY with no crystal that needs
the SoC 25 MHz reference (clk_mac_refout), so in RGMII the clock was
never enabled and the PHY did not respond on MDIO.

Request the group whenever the SoC drives the clock (clock_in_out =
"output"), not just for RMII. The clocks are optional, so other boards
are unaffected.

Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
index 8d7042e68..dd060e4b8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-rk.c
@@ -1112,7 +1112,7 @@ static int rk_gmac_clk_init(struct plat_stmmacenet_data *plat)
 	bsp_priv->clk_enabled = false;
 
 	bsp_priv->num_clks = ARRAY_SIZE(rk_clocks);
-	if (phy_iface == PHY_INTERFACE_MODE_RMII)
+	if (phy_iface == PHY_INTERFACE_MODE_RMII || !bsp_priv->clock_input)
 		bsp_priv->num_clks += ARRAY_SIZE(rk_rmii_clocks);
 
 	bsp_priv->clks = devm_kcalloc(dev, bsp_priv->num_clks,
@@ -1123,7 +1123,7 @@ static int rk_gmac_clk_init(struct plat_stmmacenet_data *plat)
 	for (i = 0; i < ARRAY_SIZE(rk_clocks); i++)
 		bsp_priv->clks[i].id = rk_clocks[i];
 
-	if (phy_iface == PHY_INTERFACE_MODE_RMII) {
+	if (phy_iface == PHY_INTERFACE_MODE_RMII || !bsp_priv->clock_input) {
 		for (j = 0; j < ARRAY_SIZE(rk_rmii_clocks); j++)
 			bsp_priv->clks[i++].id = rk_rmii_clocks[j];
 	}
-- 
2.43.0

Re: [PATCH net-next] net: stmmac: dwmac-rk: enable the reference clock for output mode

[Maxime Chevallier]

Hi,

On 7/16/26 08:56, Jiaxing Hu wrote:
> 
> rk_gmac_clk_init() only requests the refout clock group for RMII. The
> ArmSoM CM5 has an on-module YT8531 RGMII PHY with no crystal that needs
> the SoC 25 MHz reference (clk_mac_refout), so in RGMII the clock was
> never enabled and the PHY did not respond on MDIO.
> 
> Request the group whenever the SoC drives the clock (clock_in_out =
> "output"), not just for RMII. The clocks are optional, so other boards
> are unaffected.

DT binding for rockchip-dwmac says :

clock_in_out:
    description:
      For RGMII, it must be "input", means main clock(125MHz)
      is not sourced from SoC's PLL, but input from PHY.
      For RMII, "input" means PHY provides the reference clock(50MHz),
      "output" means GMAC provides the reference clock.

So the statement "For RGMII, it must be input [...]" is now incorrect :
 - it can be output for RGMII
 - it will be 25Hz if set to output, from what I get from the commit log.

Can you update it ?

Maxime

Re: [PATCH net-next] net: stmmac: dwmac-rk: enable the reference clock for output mode

[Andrew Lunn]

On Thu, Jul 16, 2026 at 06:56:06PM +1200, Jiaxing Hu wrote:
> 
> rk_gmac_clk_init() only requests the refout clock group for RMII. The
> ArmSoM CM5 has an on-module YT8531 RGMII PHY with no crystal that needs
> the SoC 25 MHz reference (clk_mac_refout), so in RGMII the clock was
> never enabled and the PHY did not respond on MDIO.

Since the PHY is the consumer of the clock, it would be better if the
PHY enabled the clock.

    Andrew

---
pw-bot: cr