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The USB core only allows up to 31 (USB_MAXCHILDREN) ports under a roothub. The xHCI driver keeps track of which ports are suspended, which ports have a suspend change bit set, and what time the port will be done resuming. It keeps track of the first two by setting a bit in a u32 variable, suspended_ports or port_c_suspend. The xHCI driver currently assumes we can have up to 256 ports under a roothub, so it allocates an array of 8 u32 variables for both suspended_ports and port_c_suspend. It also allocates a 256-element array to keep track of when the ports will be done resuming. Since we can only have 31 roothub ports, we only need to use one u32 for each of the suspend state and change variables. We simplify the bit math that's trying to index into those arrays and set the correct bit, if we assume wIndex never exceeds 30. (wIndex is zero-based after it's decremented from the value passed in from the USB core.) Finally, we change the resume_done array to only hold 31 elements. Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: Andiry Xu <andiry.xu@amd.com> |
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| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| serial | ||
| storage | ||
| wusbcore | ||
| Kconfig | ||
| Makefile | ||
| README | ||
| 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.