On Thu, 28 Jun 2012, Lan Tianyu wrote:
> This patch is to add two attributes for each usb hub ports to control port's power.
> Control port's power through setting or clearing PORT_POWER feature.
>
> control has two options. "auto", "on" and "off"
> "on" - port power must be on.
> "off" - port power must be off.
>
> state reports usb port's power state
> "on" - power on
> "off" - power off
> "error" - can't get power state
>
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -848,7 +858,9 @@ static unsigned hub_power_on(struct usb_hub *hub, bool do_delay)
> dev_dbg(hub->intfdev, "trying to enable port power on "
> "non-switchable hub\n");
> for (port1 = 1; port1 <= hub->descriptor->bNbrPorts; port1++)
> - set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);
> + if (hub->ports[port1 - 1]->port_power_policy
> + == USB_PORT_POWER_ON)
> + set_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);
Since the last patch version, I realized that sometimes host controller
drivers will turn on port power by themselves. To be safe, you should add
else
clear_port_feature(hub->hdev, port1, USB_PORT_FEAT_POWER);
> +static ssize_t
> +store_port_power_control(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
Since you have to break the line anyway, you ought to put the function's
name on the first line.
> +{
> + struct usb_device *hdev = to_usb_device(dev->parent->parent);
> + struct usb_port *hub_port = to_usb_port(dev);
> + int port1, len = count;
> + char *cp;
> +
> + sscanf(dev_name(dev), "port%d", &port1);
> + cp = memchr(buf, '\n', count);
> + if (cp)
> + len = cp - buf;
> + if (len == sizeof on_string - 1
> + && strncmp(buf, on_string, len) == 0) {
> + hub_port->port_power_policy = USB_PORT_POWER_ON;
> + set_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
> + } else if (len == sizeof off_string - 1
> + && strncmp(buf, off_string, len) == 0) {
> + hub_port->port_power_policy = USB_PORT_POWER_OFF;
> + clear_port_feature(hdev, port1, USB_PORT_FEAT_POWER);
You should return -EIO if set_port_feature or clear_port_feature fails.
Alan Stern
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
