[PATCH net v3] net: stmmac: update Rx clk divider for 10M SGMII

[Sneh Shah]

SGMII 10MBPS mode needs RX clock divider to avoid drops in Rx.
Update configure SGMII function with rx clk divider programming.

Fixes: 463120c31c58 ("net: stmmac: dwmac-qcom-ethqos: add support for SGMII")
Signed-off-by: Sneh Shah <quic_snehshah@xxxxxxxxxxx>
---
v3 changelog:
- Added comment to explain why MAC needs to be reconfigured for SGMII
v2 changelog:
- Use FIELD_PREP to prepare bifield values in place of GENMASK
- Add fixes tag
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
index d3bf42d0fceb..ab2245995bc6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-qcom-ethqos.c
@@ -34,6 +34,7 @@
 #define RGMII_CONFIG_LOOPBACK_EN		BIT(2)
 #define RGMII_CONFIG_PROG_SWAP			BIT(1)
 #define RGMII_CONFIG_DDR_MODE			BIT(0)
+#define RGMII_CONFIG_SGMII_CLK_DVDR		GENMASK(18, 10)
 
 /* SDCC_HC_REG_DLL_CONFIG fields */
 #define SDCC_DLL_CONFIG_DLL_RST			BIT(30)
@@ -598,6 +599,9 @@ static int ethqos_configure_rgmii(struct qcom_ethqos *ethqos)
 	return 0;
 }
 
+/* On interface toggle MAC registetrs gets reset.
+ * Configure MAC block for SGMII on ethernet phy link up
+ */
 static int ethqos_configure_sgmii(struct qcom_ethqos *ethqos)
 {
 	int val;
@@ -617,6 +621,9 @@ static int ethqos_configure_sgmii(struct qcom_ethqos *ethqos)
 	case SPEED_10:
 		val |= ETHQOS_MAC_CTRL_PORT_SEL;
 		val &= ~ETHQOS_MAC_CTRL_SPEED_MODE;
+		rgmii_updatel(ethqos, RGMII_CONFIG_SGMII_CLK_DVDR,
+			      FIELD_PREP(RGMII_CONFIG_SGMII_CLK_DVDR, 0x31),
+			      RGMII_IO_MACRO_CONFIG);
 		break;
 	}
 
-- 
2.17.1