Visit Our UNIX and Linux User Community

Linux and UNIX Man Pages

Test Your Knowledge in Computers #321
Difficulty: Medium
DHCP stands for Dynamic Host Configuration Port.
True or False?
Linux & Unix Commands - Search Man Pages

usb_gadget_vbus_draw(9) [centos man page]

USB_GADGET_VBUS_DRAW(9) 				      Kernel Mode Gadget API					   USB_GADGET_VBUS_DRAW(9)

NAME
usb_gadget_vbus_draw - constrain controller's VBUS power usage SYNOPSIS
int usb_gadget_vbus_draw(struct usb_gadget * gadget, unsigned mA); ARGUMENTS
gadget The device whose VBUS usage is being described mA How much current to draw, in milliAmperes. This should be twice the value listed in the configuration descriptor bMaxPower field. DESCRIPTION
This call is used by gadget drivers during SET_CONFIGURATION calls, reporting how much power the device may consume. For example, this could affect how quickly batteries are recharged. Returns zero on success, else negative errno. AUTHOR
David Brownell <dbrownell@users.sourceforge.net> Author. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 USB_GADGET_VBUS_DRAW(9)

Check Out this Related Man Page

STRUCT 
USB_GADGET(9) Kernel Mode Gadget API STRUCT USB_GADGET(9) NAME
struct_usb_gadget - represents a usb slave device SYNOPSIS
struct usb_gadget { const struct usb_gadget_ops * ops; struct usb_ep * ep0; struct list_head ep_list; enum usb_device_speed speed; unsigned is_dualspeed:1; unsigned is_otg:1; unsigned is_a_peripheral:1; unsigned b_hnp_enable:1; unsigned a_hnp_support:1; unsigned a_alt_hnp_support:1; const char * name; struct device dev; }; MEMBERS
ops Function pointers used to access hardware-specific operations. ep0 Endpoint zero, used when reading or writing responses to driver setup requests ep_list List of other endpoints supported by the device. speed Speed of current connection to USB host. is_dualspeed True if the controller supports both high and full speed operation. If it does, the gadget driver must also support both. is_otg True if the USB device port uses a Mini-AB jack, so that the gadget driver must provide a USB OTG descriptor. is_a_peripheral False unless is_otg, the "A" end of a USB cable is in the Mini-AB jack, and HNP has been used to switch roles so that the "A" device currently acts as A-Peripheral, not A-Host. b_hnp_enable OTG device feature flag, indicating that the A-Host enabled HNP support. a_hnp_support OTG device feature flag, indicating that the A-Host supports HNP at this port. a_alt_hnp_support OTG device feature flag, indicating that the A-Host only supports HNP on a different root port. name Identifies the controller hardware type. Used in diagnostics and sometimes configuration. dev Driver model state for this abstract device. DESCRIPTION
Gadgets have a mostly-portable "gadget driver" implementing device functions, handling all usb configurations and interfaces. Gadget drivers talk to hardware-specific code indirectly, through ops vectors. That insulates the gadget driver from hardware details, and packages the hardware endpoints through generic i/o queues. The "usb_gadget" and "usb_ep" interfaces provide that insulation from the hardware. Except for the driver data, all fields in this structure are read-only to the gadget driver. That driver data is part of the "driver model" infrastructure in 2.6 (and later) kernels, and for earlier systems is grouped in a similar structure that's not known to the rest of the kernel. Values of the three OTG device feature flags are updated before the setup call corresponding to USB_REQ_SET_CONFIGURATION, and before driver suspend calls. They are valid only when is_otg, and when the device is acting as a B-Peripheral (so is_a_peripheral is false). AUTHOR
David Brownell <dbrownell@users.sourceforge.net> Author. COPYRIGHT
Kernel Hackers Manual 2.6. July 2010 STRUCT USB_GADGET(9)

Featured Tech Videos