[PATCH net-next v3 3/3] net: stmmac: Return early if invalid in loongson_dwmac_fix_reset()

[Tiezhu Yang]

If the MAC controller does not connect to any PHY interface, there is a
missing clock, then the DMA reset fails.

For this case, the DMA_BUS_MODE_SFT_RESET bit is 1 before software reset,
just print an error message which gives a hint the PHY clock is missing,
and then return -EINVAL immediately to avoid waiting for the timeout when
the DMA reset fails in loongson_dwmac_fix_reset().

With this patch, for the normal end user, the computer start faster with
reducing boot time for 2 seconds on the specified mainboard.

Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
index bb376c69016d..05f195a18548 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-loongson.c
@@ -513,6 +513,11 @@ static int loongson_dwmac_fix_reset(struct stmmac_priv *priv, void __iomem *ioad
 {
 	u32 value = readl(ioaddr + DMA_BUS_MODE);
 
+	if (value & DMA_BUS_MODE_SFT_RESET) {
+		netdev_err(priv->dev, "the PHY clock is missing\n");
+		return -EINVAL;
+	}
+
 	value |= DMA_BUS_MODE_SFT_RESET;
 	writel(value, ioaddr + DMA_BUS_MODE);
 
-- 
2.42.0