net: stmmac: Support gpio high-level reset for devices requiring it

[PATCH] net: stmmac: Support gpio high-level reset for devices requiring it

Posted by Lizhe 3 months ago

some devices only reset when the GPIO is at a high level, but the
current function lacks support for such devices. add high-level
reset functionality to the function to support devices that require
high-level triggering for reset

Signed-off-by: Lizhe <sensor1010@163.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index 836f2848dfeb..cb989e6d7eac 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -458,6 +458,7 @@ int stmmac_mdio_reset(struct mii_bus *bus)
 
 #ifdef CONFIG_OF
 	if (priv->device->of_node) {
+		int active_low = 0;
 		struct gpio_desc *reset_gpio;
 		u32 delays[3] = { 0, 0, 0 };
 
@@ -467,6 +468,9 @@ int stmmac_mdio_reset(struct mii_bus *bus)
 		if (IS_ERR(reset_gpio))
 			return PTR_ERR(reset_gpio);
 
+		if (reset_gpio)
+			active_low = gpiod_is_active_low(reset_gpio);
+
 		device_property_read_u32_array(priv->device,
 					       "snps,reset-delays-us",
 					       delays, ARRAY_SIZE(delays));
@@ -474,11 +478,11 @@ 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(reset_gpio, active_low ? 1 : 0);
 		if (delays[1])
 			msleep(DIV_ROUND_UP(delays[1], 1000));
 
-		gpiod_set_value_cansleep(reset_gpio, 0);
+		gpiod_set_value_cansleep(reset_gpio, active_low ? 0 : 1);
 		if (delays[2])
 			msleep(DIV_ROUND_UP(delays[2], 1000));
 	}
-- 
2.17.1

Re: [PATCH] net: stmmac: Support gpio high-level reset for devices requiring it

Posted by Russell King (Oracle) 3 months ago

On Tue, Jul 08, 2025 at 09:50:44AM -0700, Lizhe wrote:
> some devices only reset when the GPIO is at a high level, but the
> current function lacks support for such devices. add high-level
> reset functionality to the function to support devices that require
> high-level triggering for reset
> 
> Signed-off-by: Lizhe <sensor1010@163.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> index 836f2848dfeb..cb989e6d7eac 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> @@ -458,6 +458,7 @@ int stmmac_mdio_reset(struct mii_bus *bus)
>  
>  #ifdef CONFIG_OF
>  	if (priv->device->of_node) {
> +		int active_low = 0;
>  		struct gpio_desc *reset_gpio;
>  		u32 delays[3] = { 0, 0, 0 };
>  
> @@ -467,6 +468,9 @@ int stmmac_mdio_reset(struct mii_bus *bus)
>  		if (IS_ERR(reset_gpio))
>  			return PTR_ERR(reset_gpio);
>  
> +		if (reset_gpio)
> +			active_low = gpiod_is_active_low(reset_gpio);
> +
>  		device_property_read_u32_array(priv->device,
>  					       "snps,reset-delays-us",
>  					       delays, ARRAY_SIZE(delays));
> @@ -474,11 +478,11 @@ 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(reset_gpio, active_low ? 1 : 0);
>  		if (delays[1])
>  			msleep(DIV_ROUND_UP(delays[1], 1000));
>  
> -		gpiod_set_value_cansleep(reset_gpio, 0);
> +		gpiod_set_value_cansleep(reset_gpio, active_low ? 0 : 1);
>  		if (delays[2])
>  			msleep(DIV_ROUND_UP(delays[2], 1000));
>  	}

NAK. Not required. The GPIO layer can cope with active-high and
active-low signals declared in firmware without needing driver
modification. Use the right data in the firmware and you don't
need to patch.

/* Bit 0 express polarity */
#define GPIO_ACTIVE_HIGH 0
#define GPIO_ACTIVE_LOW 1

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

Re: [PATCH] net: stmmac: Support gpio high-level reset for devices requiring it

Posted by Andrew Lunn 3 months ago

On Tue, Jul 08, 2025 at 09:50:44AM -0700, Lizhe wrote:
> some devices only reset when the GPIO is at a high level, but the
> current function lacks support for such devices. add high-level
> reset functionality to the function to support devices that require
> high-level triggering for reset

You can probably specify this in DT:

reset-gpios = <&qe_pio_e 18 GPIO_ACTIVE_LOW>;

The gpio core will then flip the meaning of

gpiod_set_value_cansleep(reset_gpio, 1);

such that a value of 1 will become low, 0 will become high.

     Andrew