[PATCH v2] net: stmmac: avoid repeated devm_gpiod_get_optional in mdio

[Liu Xiang <liu.xiang@zlingsmart.com>]

During system resume, stmmac_resume() calls stmmac_mdio_reset().
This results in repeated calls to devm_gpiod_get_optional() for the same
GPIO. The second invocation returns an error since the GPIO descriptor has
already been obtained.

Signed-off-by: Liu Xiang <liu.xiang@zlingsmart.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h   |  2 ++
 .../net/ethernet/stmicro/stmmac/stmmac_mdio.c  | 18 +++++++++---------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 33667a267..34ebc6f3a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -372,6 +372,8 @@ struct stmmac_priv {
 	struct bpf_prog *xdp_prog;
 
 	struct devlink *devlink;
+
+	struct gpio_desc *reset_gpio;
 };
 
 enum stmmac_state {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index a7c2496b3..d85cfb044 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -386,15 +386,15 @@ int stmmac_mdio_reset(struct mii_bus *bus)
 
 #ifdef CONFIG_OF
 	if (priv->device->of_node) {
-		struct gpio_desc *reset_gpio;
 		u32 delays[3] = { 0, 0, 0 };
 
-		reset_gpio = devm_gpiod_get_optional(priv->device,
-						     "snps,reset",
-						     GPIOD_OUT_LOW);
-		if (IS_ERR(reset_gpio))
-			return PTR_ERR(reset_gpio);
-
+		if (IS_ERR_OR_NULL(priv->reset_gpio)) {
+			priv->reset_gpio = devm_gpiod_get_optional(priv->device,
+								   "snps,reset",
+								 GPIOD_OUT_LOW);
+			if (IS_ERR(priv->reset_gpio))
+				return PTR_ERR(priv->reset_gpio);
+		}
 		device_property_read_u32_array(priv->device,
 					       "snps,reset-delays-us",
 					       delays, ARRAY_SIZE(delays));
@@ -402,11 +402,11 @@ int stmmac_mdio_reset(struct mii_bus *bus)
 		if (delays[0])
 			msleep(DIV_ROUND_UP(delays[0], 1000));
 
-		gpiod_set_value_cansleep(reset_gpio, 1);
+		gpiod_set_value_cansleep(priv->reset_gpio, 1);
 		if (delays[1])
 			msleep(DIV_ROUND_UP(delays[1], 1000));
 
-		gpiod_set_value_cansleep(reset_gpio, 0);
+		gpiod_set_value_cansleep(priv->reset_gpio, 0);
 		if (delays[2])
 			msleep(DIV_ROUND_UP(delays[2], 1000));
 	}
-- 
2.34.1