forked from Minki/linux
88fafff9d7
Wireless USB Host Controllers accept a large number of devices per
host, which shows up as a large number of ports in its root hub.
When the number of ports in a hub device goes over 16, the activation
of the hub fails with the cryptic message in klogd.
hub 2-0:1.0: activate --> -22
Following this further, it was seen that:
hub_probe()
hub_configure()
generates pipe number
pseudo allocates buffer 'maxp' bytes in size using usb_maxpacket()
The endpoint descriptor for a root hub interrupt endpoint is
declared in
drivers/usb/core/hcd.c:hs_rh_config_descriptor and declares it
to be size two (supporting 15 devices max).
hub_activate()
usb_hcd_submit_urb()
rh_urb_enqueue()
urb->pipe is neither int nor ctl, so it errors out
rh_queue_status()
Returns -EINVAL because the buffer length is smaller
than the minimum needed to report all the hub port
bits as in accordance with USB2.0[11.12.3]. There has
to be trunc((PORTS + 1 + 7) / 8) bytes of space at
least.
Alan Stern confirmed that the reason for reading maxpktsize and not
the right amount is because some hubs are known to return more data
and thus cause overflow.
So this patch simply changes the code to make the interrupt endpoint's
max packet size be at least the minimum required by USB_MAXCHILDREN
(instead of a fixed magic number) and add documentation for that. This
way we are always ahead of the limit.
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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| .. | ||
| atm | ||
| class | ||
| core | ||
| gadget | ||
| host | ||
| image | ||
| input | ||
| misc | ||
| mon | ||
| net | ||
| serial | ||
| storage | ||
| 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.