net: stmmac: make reset control an optional requirement

Not having a reset control line to the ethernet controller should not be a
hard failure. Instead, add support for deferred probing and just print out
a debug statement.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Vince Bridgers <vbridger@opensource.altera.com>
CC: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
index e97074cd5800..5a36bd2c7837 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c
@@ -91,7 +91,9 @@ static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *
                                                   STMMAC_RESOURCE_NAME);
         if (IS_ERR(dwmac->stmmac_rst)) {
                 dev_info(dev, "Could not get reset control!\n");
-                return -EINVAL;
+                if (PTR_ERR(dwmac->stmmac_rst) == -EPROBE_DEFER)
+                        return -EPROBE_DEFER;
+                dwmac->stmmac_rst = NULL;
         }
 
         dwmac->interface = of_get_phy_mode(np);