[PATCH net-next 1/2] net: stmmac: Make MDIO bus reset optional

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

The Tegra EQOS driver already resets the MDIO bus at probe time via the
reset GPIO specified in the phy-reset-gpios device tree property. There
is no need to reset the bus again later on.

This avoids the need to query the device tree for the snps,reset GPIO,
which is not part of the Tegra EQOS device tree bindings. This quiesces
an error message from the generic bus reset code if it doesn't find the
snps,reset related delays.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c | 3 +++
 drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c       | 4 +++-
 drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c        | 1 +
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c   | 8 +++++++-
 include/linux/stmmac.h                                  | 1 +
 5 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
index 3a14cdd01f5f..66933332c68e 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c
@@ -333,6 +333,9 @@ static void *tegra_eqos_probe(struct platform_device *pdev,
 	usleep_range(2000, 4000);
 	gpiod_set_value(eqos->reset, 0);
 
+	/* MDIO bus was already reset just above */
+	data->mdio_bus_data->needs_reset = false;
+
 	eqos->rst = devm_reset_control_get(&pdev->dev, "eqos");
 	if (IS_ERR(eqos->rst)) {
 		err = PTR_ERR(eqos->rst);
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index 4304c1abc5d1..40c42637ad75 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -348,7 +348,9 @@ int stmmac_mdio_register(struct net_device *ndev)
 		max_addr = PHY_MAX_ADDR;
 	}
 
-	new_bus->reset = &stmmac_mdio_reset;
+	if (mdio_bus_data->needs_reset)
+		new_bus->reset = &stmmac_mdio_reset;
+
 	snprintf(new_bus->id, MII_BUS_ID_SIZE, "%s-%x",
 		 new_bus->name, priv->plat->bus_id);
 	new_bus->priv = ndev;
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
index 86f9c07a38cf..d5d08e11c353 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pci.c
@@ -63,6 +63,7 @@ static void common_default_data(struct plat_stmmacenet_data *plat)
 	plat->has_gmac = 1;
 	plat->force_sf_dma_mode = 1;
 
+	plat->mdio_bus_data->needs_reset = true;
 	plat->mdio_bus_data->phy_mask = 0;
 
 	/* Set default value for multicast hash bins */
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 73fc2524372e..333b09564b88 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -342,10 +342,16 @@ static int stmmac_dt_phy(struct plat_stmmacenet_data *plat,
 		mdio = true;
 	}
 
-	if (mdio)
+	if (mdio) {
 		plat->mdio_bus_data =
 			devm_kzalloc(dev, sizeof(struct stmmac_mdio_bus_data),
 				     GFP_KERNEL);
+		if (!plat->mdio_bus_data)
+			return -ENOMEM;
+
+		plat->mdio_bus_data->needs_reset = true;
+	}
+
 	return 0;
 }
 
diff --git a/include/linux/stmmac.h b/include/linux/stmmac.h
index 7d06241582dd..7b3e354bcd3c 100644
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -81,6 +81,7 @@ struct stmmac_mdio_bus_data {
 	unsigned int phy_mask;
 	int *irqs;
 	int probed_phy_irq;
+	bool needs_reset;
 };
 
 struct stmmac_dma_cfg {
-- 
2.22.0