From: Edward Cree <ecree@solarflare.com>
Date: Mon, 3 Aug 2020 21:32:16 +0100
Subject: sfc_ef100: fail the probe if NIC uses unsol_ev credits
Patch-mainline: v5.9-rc1
Git-commit: 4496363bec32df36df51db7f915a11d3b38615e3
References: jsc#SLE-16683

In the future, EF100 is planned to have a credit-based scheme for
 handling unsolicited events, which drivers will need to use in order
 to function correctly.  However, current EF100 hardware does not yet
 generate unsolicited events and the credit scheme has not yet been
 implemented in firmware.  To prevent compatibility problems later if
 the current driver is used with future firmware which does implement
 it, we check for the corresponding capability flag (which that
 future firmware will set), and if found, we refuse to probe.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/sfc/ef100_nic.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/net/ethernet/sfc/ef100_nic.c
+++ b/drivers/net/ethernet/sfc/ef100_nic.c
@@ -602,6 +602,12 @@ static int ef100_probe_main(struct efx_n
 		goto fail;
 	}
 
+	if (efx_has_cap(efx, UNSOL_EV_CREDIT_SUPPORTED)) {
+		netif_info(efx, drv, efx->net_dev, "Firmware uses unsolicited-event credits\n");
+		rc = -EINVAL;
+		goto fail;
+	}
+
 	rc = ef100_phy_probe(efx);
 	if (rc)
 		goto fail;