sfc: Clear RXIN_SEL when soft-resetting QT2025C

When we enable PMA/PMD loopback this automatically sets RXIN_SEL
(inverse polarity for RXIN).  We need to clear that bit during the
soft-reset sequence, as it is not done automatically.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/sfc/qt202x_phy.c

@@ -41,6 +41,8 @@
 #define PCS_UC_STATUS_LBN	0
 #define PCS_UC_STATUS_WIDTH	8
 #define PCS_UC_STATUS_FW_SAVE	0x20
+#define PMA_PMD_MODE_REG	0xc301
+#define PMA_PMD_RXIN_SEL_LBN	6
 #define PMA_PMD_FTX_CTRL2_REG	0xc309
 #define PMA_PMD_FTX_STATIC_LBN	13
 #define PMA_PMD_VEND1_REG	0xc001
@@ -282,6 +284,10 @@ static int qt2025c_select_phy_mode(struct efx_nic *efx)
 	 * slow) reload of the firmware image (the microcontroller's code
 	 * memory is not affected by the microcontroller reset). */
 	efx_mdio_write(efx, 1, 0xc317, 0x00ff);
+	/* PMA/PMD loopback sets RXIN to inverse polarity and the firmware
+	 * restart doesn't reset it. We need to do that ourselves. */
+	efx_mdio_set_flag(efx, 1, PMA_PMD_MODE_REG,
+			  1 << PMA_PMD_RXIN_SEL_LBN, false);
 	efx_mdio_write(efx, 1, 0xc300, 0x0002);
 	msleep(20);