diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2012-12-18 15:25:46 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-11 16:16:01 -0800 |
| commit | 8d8479db3dde3ef7a9bc803e565842764fa21a53 (patch) | |
| tree | 6c4e2b049c675b62be0fd3d65ae606f367dfb56c /drivers/usb/core/usb.h | |
| parent | ece1d77ed73b335319725f1d5ffa72ca3fa9b05c (diff) | |
usb/core: consider link speed while looking at bMaxPower
The USB 2.0 specification says that bMaxPower is the maximum power
consumption expressed in 2 mA units and the USB 3.0 specification says
that it is expressed in 8 mA units.
This patch adds a helper function usb_get_max_power() which computes the
value based on config & usb_device's speed value. The the device descriptor
dump computes the value on its own.
Cc: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/usb.h')
| -rw-r--r-- | drivers/usb/core/usb.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/usb/core/usb.h b/drivers/usb/core/usb.h index 1c528c1bf0be..fb7d8fcb4551 100644 --- a/drivers/usb/core/usb.h +++ b/drivers/usb/core/usb.h @@ -38,6 +38,15 @@ extern char *usb_cache_string(struct usb_device *udev, int index); extern int usb_set_configuration(struct usb_device *dev, int configuration); extern int usb_choose_configuration(struct usb_device *udev); +static inline unsigned usb_get_max_power(struct usb_device *udev, + struct usb_host_config *c) +{ + /* SuperSpeed power is in 8 mA units; others are in 2 mA units */ + unsigned mul = (udev->speed == USB_SPEED_SUPER ? 8 : 2); + + return c->desc.bMaxPower * mul; +} + extern void usb_kick_khubd(struct usb_device *dev); extern int usb_match_one_id_intf(struct usb_device *dev, struct usb_host_interface *intf, |