4ee823b83b
USB 3.0 hubs don't have a port suspend change bit (that bit is now reserved). Instead, when a host-initiated resume finishes, the hub sets the port link state change bit. When a USB 3.0 device initiates remote wakeup, the parent hubs with their upstream links in U3 will pass the LFPS up the chain. The first hub that has an upstream link in U0 (which may be the roothub) will reflect that LFPS back down the path to the device. However, the parent hubs in the resumed path will not set their link state change bit. Instead, the device that initiated the resume has to send an asynchronous "Function Wake" Device Notification up to the host controller. Therefore, we need a way to notify the USB core of a device resume without going through the normal hub URB completion method. First, make the xHCI roothub act like an external USB 3.0 hub and not pass up the port link state change bit when a device-initiated resume finishes. Introduce a new xHCI bit field, port_remote_wakeup, so that we can tell the difference between a port coming out of the U3Exit state (host-initiated resume) and the RExit state (ending state of device-initiated resume). Since the USB core can't tell whether a port on a hub has resumed by looking at the Hub Status buffer, we need to introduce a bitfield, wakeup_bits, that indicates which ports have resumed. When the xHCI driver notices a port finishing a device-initiated resume, we call into a new USB core function, usb_wakeup_notification(), that will set the right bit in wakeup_bits, and kick khubd for that hub. We also call usb_wakeup_notification() when the Function Wake Device Notification is received by the xHCI driver. This covers the case where the link between the roothub and the first-tier hub is in U0, and the hub reflects the resume signaling back to the device without giving any indication it has done so until the device sends the Function Wake notification. Change the code in khubd that handles the remote wakeup to look at the state the USB core thinks the device is in, and handle the remote wakeup if the port's wakeup bit is set. This patch only takes care of the case where the device is attached directly to the roothub, or the USB 3.0 hub that is attached to the root hub is the device sending the Function Wake Device Notification (e.g. because a new USB device was attached). The other cases will be covered in a second patch. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> |
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| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| renesas_usbhs | ||
| serial | ||
| storage | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| usb-common.c | ||
| usb-skeleton.c | ||
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.