[PATCH 3/4] usb: onboard-hub: Add support for multiple power supplies

[Quentin Schulz]

Hi Lukasz,

On 4/25/25 12:56 PM, Lukasz Czechowski wrote:
> Some of the onboard hubs require multiple power supplies, so extend
> the driver to support them.
> The implementation is inspired by the kernel driver, as introduced
> by commit [1] in the v6.10 kernel.
> 
> [1] https://github.com/torvalds/linux/commit/ec1848cd5df426f57a7f6a8a6b95b69259c52cfc
> Signed-off-by: Lukasz Czechowski <lukasz.czechowski at thaumatec.com>
> ---
>   common/usb_onboard_hub.c | 45 +++++++++++++++++++++++++++++++++------------
>   1 file changed, 33 insertions(+), 12 deletions(-)
> 
> diff --git a/common/usb_onboard_hub.c b/common/usb_onboard_hub.c
> index 325c274ed952..b8fa38a4111d 100644
> --- a/common/usb_onboard_hub.c
> +++ b/common/usb_onboard_hub.c
> @@ -20,14 +20,18 @@
>   #define USB5744_CONFIG_REG_ACCESS	0x0037
>   #define USB5744_CONFIG_REG_ACCESS_LSB	0x99
>   
> +#define MAX_SUPPLIES 2
> +
>   struct onboard_hub {
> -	struct udevice *vdd;
> +	struct udevice *vdd[MAX_SUPPLIES];
>   	struct gpio_desc *reset_gpio;
>   };
>   
>   struct onboard_hub_data {
>   	unsigned long reset_us;
>   	unsigned long power_on_delay_us;
> +	unsigned int num_supplies;
> +	const char * const supply_names[MAX_SUPPLIES];
>   	int (*init)(struct udevice *dev);
>   };
>   
> @@ -144,20 +148,28 @@ static int usb_onboard_hub_probe(struct udevice *dev)
>   	struct onboard_hub_data *data =
>   		(struct onboard_hub_data *)dev_get_driver_data(dev);
>   	struct onboard_hub *hub = dev_get_priv(dev);
> +	unsigned int i;
>   	int ret;
>   
> -	ret = device_get_supply_regulator(dev, "vdd-supply", &hub->vdd);
> -	if (ret && ret != -ENOENT) {
> -		dev_err(dev, "can't get vdd-supply: %d\n", ret);
> -		return ret;
> +	if (data->num_supplies > MAX_SUPPLIES) {
> +		dev_err(dev, "invalid supplies number, max supported: %d\n", MAX_SUPPLIES);
> +		return -EINVAL;
>   	}
>   
> -	if (hub->vdd) {
> -		ret = regulator_set_enable_if_allowed(hub->vdd, true);
> -		if (ret && ret != -ENOSYS) {
> -			dev_err(dev, "can't enable vdd-supply: %d\n", ret);
> +	for (i = 0; i < data->num_supplies; i++) {
> +		ret = device_get_supply_regulator(dev, data->supply_names[i], &hub->vdd[i]);
> +		if (ret && ret != -ENOENT) {
> +			dev_err(dev, "can't get %s: %d\n", data->supply_names[i], ret);
>   			return ret;
>   		}
> +
> +		if (hub->vdd[i]) {
> +			ret = regulator_set_enable_if_allowed(hub->vdd[i], true);
> +			if (ret && ret != -ENOSYS) {
> +				dev_err(dev, "can't enable %s: %d\n", data->supply_names[i], ret);
> +				return ret;
> +			}
> +		}

I'm wondering if we shouldn't have all return ret; actually be goto err; 
instead? I would assume that the error path in the probe function should 
be really close to what we have in remove function?

To that extent, before this patch even, I think we should probably 
dm_gpio_set_value() the reset line when there's an error so that the hub 
is held in reset?

Additionally, I believe the dm_gpio_free() in the remove function is 
unnecessary because we request the gpio with a devm_ function which 
should call dm_gpio_free() whenever appropriate?

Finally, specifically for this patch here, I believe we should disable 
all regulators in the opposite order when in the error path?

Something like:

err:
     for (i = data->num_supplies - 1; i >= 0; i--) {
         ret = regulator_set_enable_if_allowed(hub->vdd[i], false);
         if (ret)
             dev_err(dev, "can't disable %s: %d\n", 
data->supply_names[i], ret);
     }

? what do you think?

>   	}
>   
>   	ret = usb_onboard_hub_reset(dev);
> @@ -208,7 +220,10 @@ static int usb_onboard_hub_bind(struct udevice *dev)
>   
>   static int usb_onboard_hub_remove(struct udevice *dev)
>   {
> +	struct onboard_hub_data *data =
> +		(struct onboard_hub_data *)dev_get_driver_data(dev);
>   	struct onboard_hub *hub = dev_get_priv(dev);
> +	unsigned int i;
>   	int ret;
>   
>   	if (hub->reset_gpio) {
> @@ -216,9 +231,11 @@ static int usb_onboard_hub_remove(struct udevice *dev)
>   		dm_gpio_free(hub->reset_gpio->dev, hub->reset_gpio);
>   	}
>   
> -	ret = regulator_set_enable_if_allowed(hub->vdd, false);
> -	if (ret)
> -		dev_err(dev, "can't disable vdd-supply: %d\n", ret);
> +	for (i = 0; i < data->num_supplies; i++) {
> +		ret = regulator_set_enable_if_allowed(hub->vdd[i], false);
> +		if (ret)
> +			dev_err(dev, "can't disable %s: %d\n", data->supply_names[i], ret);
> +	}
>   

The error/remove path is usually unwinding in opposite order than the 
normal path, so that would be looping from last supply to first. C.f. 
regulator_bulk_disable in the Linux kernel.

>   	return ret;

This one's an issue now, it'll return 0 if the last 
regulator_set_enable_if_allowed is 0, overriding the return code from 
dm_gpio_set_value and earlier regulator_set_enable_if_allowed calls. We 
should probably |= them or return some appropriate hardcoded value if at 
least one failed.

Cheers,
Quentin