Re: [PATCH v3] usb: host: ehci-platform: add support for optional external vbus supply

[Robin Murphy <robin.murphy@arm.com>]

Hi Amelie,

Just a couple of drive-by coding style comments...

On 23/02/18 13:46, Amelie Delaunay wrote:
> On some boards, especially when vbus supply requires large current,
> and the charge pump on the PHY isn't enough, an external vbus power switch
> may be used.
> Add support for optional external vbus supply per port in ehci-platform.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
> 
> ---
> Changes in v3:
>   * Address Felipe Balbi comments: reduce indentation in
>     ehci_platform_port_power.
>   * Address Roger Quadros and Alan Stern comments: platforms can have one
>     external vbus supply per port, so add support to get as many optional
>     regulator as implemented ports on the host controller.
> 
> Changes in v2:
>   * Address Roger Quadros comments: move regulator_enable/disable from
>     ehci_platform_power_on/off to ehci_platform_port_power.
> ---
>   Documentation/devicetree/bindings/usb/usb-ehci.txt |  1 +
>   drivers/usb/host/ehci-platform.c                   | 52 +++++++++++++++++++++-
>   2 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/usb/usb-ehci.txt b/Documentation/devicetree/bindings/usb/usb-ehci.txt
> index 3efde12..cd576db 100644
> --- a/Documentation/devicetree/bindings/usb/usb-ehci.txt
> +++ b/Documentation/devicetree/bindings/usb/usb-ehci.txt
> @@ -19,6 +19,7 @@ Optional properties:
>    - phys : phandle + phy specifier pair
>    - phy-names : "usb"
>    - resets : phandle + reset specifier pair
> + - portN_vbus-supply : phandle of regulator supplying vbus for port N
>   
>   Example (Sequoia 440EPx):
>       ehci@e0000300 {
> diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
> index b065a96..8e9f201 100644
> --- a/drivers/usb/host/ehci-platform.c
> +++ b/drivers/usb/host/ehci-platform.c
> @@ -29,6 +29,7 @@
>   #include <linux/of.h>
>   #include <linux/phy/phy.h>
>   #include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
>   #include <linux/reset.h>
>   #include <linux/usb.h>
>   #include <linux/usb/hcd.h>
> @@ -46,6 +47,7 @@ struct ehci_platform_priv {
>   	struct reset_control *rsts;
>   	struct phy **phys;
>   	int num_phys;
> +	struct regulator **vbus_supplies;
>   	bool reset_on_resume;
>   };
>   
> @@ -56,7 +58,8 @@ static int ehci_platform_reset(struct usb_hcd *hcd)
>   	struct platform_device *pdev = to_platform_device(hcd->self.controller);
>   	struct usb_ehci_pdata *pdata = dev_get_platdata(&pdev->dev);
>   	struct ehci_hcd *ehci = hcd_to_ehci(hcd);
> -	int retval;
> +	struct ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
> +	int portnum, n_ports, retval;
>   
>   	ehci->has_synopsys_hc_bug = pdata->has_synopsys_hc_bug;
>   
> @@ -71,11 +74,57 @@ static int ehci_platform_reset(struct usb_hcd *hcd)
>   	if (retval)
>   		return retval;
>   
> +	n_ports = HCS_N_PORTS(ehci->hcs_params);
> +	priv->vbus_supplies = devm_kcalloc(&pdev->dev, n_ports,
> +					   sizeof(struct regulator *),

Using "sizeof(*priv->vbus_supplies)" here will prevent people sending 
annoying cleanup patches later.

> +					   GFP_KERNEL);
> +	if (!priv->vbus_supplies)
> +		return -ENOMEM;
> +
> +	for (portnum = 0; portnum < n_ports; portnum++) {
> +		struct regulator *vbus_supply;
> +		char id[20];
> +
> +		sprintf(id, "port%d_vbus", portnum);
> +
> +		vbus_supply = devm_regulator_get_optional(&pdev->dev, id);
> +		if (IS_ERR(vbus_supply)) {
> +			retval = PTR_ERR(vbus_supply);
> +			if (retval == -ENODEV)
> +				priv->vbus_supplies[portnum] = NULL;

The array element here hasn't yet been assigned to since kcalloc() 
initially zeroed it, so this is entirely redundant - you can simply make 
the comparison a "!=" and remove the "else" case.

Robin.

> +			else
> +				return retval;
> +		} else {
> +			priv->vbus_supplies[portnum] = vbus_supply;
> +		}
> +	}
> +
>   	if (pdata->no_io_watchdog)
>   		ehci->need_io_watchdog = 0;
>   	return 0;
>   }
>   
> +static int ehci_platform_port_power(struct usb_hcd *hcd, int portnum,
> +				    bool enable)
> +{
> +	struct ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
> +	int ret;
> +
> +	if (!priv->vbus_supplies[portnum])
> +		return 0;
> +
> +	if (enable)
> +		ret = regulator_enable(priv->vbus_supplies[portnum]);
> +	else
> +		ret = regulator_disable(priv->vbus_supplies[portnum]);
> +	if (ret)
> +		dev_err(hcd->self.controller,
> +			"failed to %s vbus supply for port %d: %d\n",
> +			enable ? "enable" : "disable", portnum, ret);
> +
> +	return ret;
> +}
> +
>   static int ehci_platform_power_on(struct platform_device *dev)
>   {
>   	struct usb_hcd *hcd = platform_get_drvdata(dev);
> @@ -134,6 +183,7 @@ static struct hc_driver __read_mostly ehci_platform_hc_driver;
>   static const struct ehci_driver_overrides platform_overrides __initconst = {
>   	.reset =		ehci_platform_reset,
>   	.extra_priv_size =	sizeof(struct ehci_platform_priv),
> +	.port_power =		ehci_platform_port_power,
>   };
>   
>   static struct usb_ehci_pdata ehci_platform_defaults = {
>