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ad493e5e58
This patch is to add usb port auto power off mechanism. When usb device is suspending, usb core will suspend usb port and usb port runtime pm callback will clear PORT_POWER feature to power off port if all conditions were met. These conditions are remote wakeup disable, pm qos NO_POWER_OFF flag clear and persist enable. When it resumes, power on port again. Add did_runtime_put in the struct usb_port to ensure pm_runtime_get/put(portdev) to be called pairedly. Set did_runtime_put to true when call pm_runtime_put(portdev) during suspending. The pm_runtime_get(portdev) only will be called when did_runtime_put is set to true during resuming. Set did_runtime_put to false after calling pm_runtime_get(portdev). Make clear_port_feature() and hdev_to_hub() as global symbol. Rename clear_port_feature() to usb_clear_port_feature() and hdev_to_hub() to usb_hub_to_struct_hub(). Extend hub_port_debounce() with the fuction of debouncing to be connected. Add two wraps: hub_port_debounce_be_connected() and hub_port_debouce_be_stable(). Increase HUB_DEBOUNCE_TIMEOUT to 2000 because some usb ssds needs around 1.5 or more to make the hub port status to be connected steadily after being powered off and powered on. Acked-by: Alan Stern <stern@rowland.harvard.edu> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Lan Tianyu <tianyu.lan@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To understand all the Linux-USB framework, you'll use these resources:
* This source code. This is necessarily an evolving work, and
includes kerneldoc that should help you get a current overview.
("make pdfdocs", and then look at "usb.pdf" for host side and
"gadget.pdf" for peripheral side.) Also, Documentation/usb has
more information.
* The USB 2.0 specification (from www.usb.org), with supplements
such as those for USB OTG and the various device classes.
The USB specification has a good overview chapter, and USB
peripherals conform to the widely known "Chapter 9".
* Chip specifications for USB controllers. Examples include
host controllers (on PCs, servers, and more); peripheral
controllers (in devices with Linux firmware, like printers or
cell phones); and hard-wired peripherals like Ethernet adapters.
* Specifications for other protocols implemented by USB peripheral
functions. Some are vendor-specific; others are vendor-neutral
but just standardized outside of the www.usb.org team.
Here is a list of what each subdirectory here is, and what is contained in
them.
core/ - This is for the core USB host code, including the
usbfs files and the hub class driver ("khubd").
host/ - This is for USB host controller drivers. This
includes UHCI, OHCI, EHCI, and others that might
be used with more specialized "embedded" systems.
gadget/ - This is for USB peripheral controller drivers and
the various gadget drivers which talk to them.
Individual USB driver directories. A new driver should be added to the
first subdirectory in the list below that it fits into.
image/ - This is for still image drivers, like scanners or
digital cameras.
../input/ - This is for any driver that uses the input subsystem,
like keyboard, mice, touchscreens, tablets, etc.
../media/ - This is for multimedia drivers, like video cameras,
radios, and any other drivers that talk to the v4l
subsystem.
../net/ - This is for network drivers.
serial/ - This is for USB to serial drivers.
storage/ - This is for USB mass-storage drivers.
class/ - This is for all USB device drivers that do not fit
into any of the above categories, and work for a range
of USB Class specified devices.
misc/ - This is for all USB device drivers that do not fit
into any of the above categories.