net: stmmac: fix get_hw_feature() on old hardware

Some old IPs do not provide the hardware feature register.
On these IPs, this register is read 0x00000000.

In old driver version, this feature was handled but a regression came
with the commit f10a6a3541b4 ("stmmac: rework get_hw_feature function").
Indeed, this commit removes the return value in dma->get_hw_feature().
This return value was used to indicate the validity of retrieved
information and used later on in stmmac_hw_init() to override
priv->plat data if this hardware feature were valid.

This patch restores the return code in ->get_hw_feature() in order
to indicate the hardware feature validity and override priv->plat
data only if this hardware feature is valid.

Fixes: f10a6a3541b4 ("stmmac: rework get_hw_feature function")
Signed-off-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
index 906e985441a9..5e98355f422b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_dma.c
@@ -371,8 +371,8 @@ static int dwxgmac2_dma_interrupt(void __iomem *ioaddr,
 	return ret;
 }
 
-static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
-				    struct dma_features *dma_cap)
+static int dwxgmac2_get_hw_feature(void __iomem *ioaddr,
+				   struct dma_features *dma_cap)
 {
 	u32 hw_cap;
 
@@ -445,6 +445,8 @@ static void dwxgmac2_get_hw_feature(void __iomem *ioaddr,
 	dma_cap->frpes = (hw_cap & XGMAC_HWFEAT_FRPES) >> 11;
 	dma_cap->frpbs = (hw_cap & XGMAC_HWFEAT_FRPPB) >> 9;
 	dma_cap->frpsel = (hw_cap & XGMAC_HWFEAT_FRPSEL) >> 3;
+
+	return 0;
 }
 
 static void dwxgmac2_rx_watchdog(void __iomem *ioaddr, u32 riwt, u32 queue)