bnxt_en: Skip disabling autoneg before PHY loopback when appropriate.

New firmware allows PHY loopback to be set without disabling autoneg
first.  Check this capability and skip disabling autoneg when
it is supported by firmware.  Using this scheme, loopback will
always work even if the PHY only supports autoneg.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -8419,7 +8419,8 @@ static int bnxt_hwrm_phy_qcaps(struct bnxt *bp)
 
 	bp->flags &= ~BNXT_FLAG_EEE_CAP;
 	if (bp->test_info)
-		bp->test_info->flags &= ~BNXT_TEST_FL_EXT_LPBK;
+		bp->test_info->flags &= ~(BNXT_TEST_FL_EXT_LPBK |
+					  BNXT_TEST_FL_AN_PHY_LPBK);
 	if (bp->hwrm_spec_code < 0x10201)
 		return 0;
 
@@ -8445,6 +8446,10 @@ static int bnxt_hwrm_phy_qcaps(struct bnxt *bp)
 		if (bp->test_info)
 			bp->test_info->flags |= BNXT_TEST_FL_EXT_LPBK;
 	}
+	if (resp->flags & PORT_PHY_QCAPS_RESP_FLAGS_AUTONEG_LPBK_SUPPORTED) {
+		if (bp->test_info)
+			bp->test_info->flags |= BNXT_TEST_FL_AN_PHY_LPBK;
+	}
 	if (resp->supported_speeds_auto_mode)
 		link_info->support_auto_speeds =
 			le16_to_cpu(resp->supported_speeds_auto_mode);

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -1226,7 +1226,8 @@ struct bnxt_led_info {
 struct bnxt_test_info {
 	u8 offline_mask;
 	u8 flags;
-#define BNXT_TEST_FL_EXT_LPBK	0x1
+#define BNXT_TEST_FL_EXT_LPBK		0x1
+#define BNXT_TEST_FL_AN_PHY_LPBK	0x2
 	u16 timeout;
 	char string[BNXT_MAX_TEST][ETH_GSTRING_LEN];
 };

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

@@ -2698,7 +2698,8 @@ static int bnxt_disable_an_for_lpbk(struct bnxt *bp,
 	u16 fw_speed;
 	int rc;
 
-	if (!link_info->autoneg)
+	if (!link_info->autoneg ||
+	    (bp->test_info->flags & BNXT_TEST_FL_AN_PHY_LPBK))
 		return 0;
 
 	rc = bnxt_query_force_speeds(bp, &fw_advertising);