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6d1d051330
The USB 3.0 specification says that sending a Set Feature or Clear
Feature for U1/U2 Enable is not a valid request when the device is in
the Default or Addressed state. It is only valid when the device is in
the Configured state.
The original LPM patch attempted to disable LPM after the device had
been reset by hub_port_init(), before it had the configuration
reinstalled. The TI hub I tested with did not fail the Clear Feature
U1/U2 Enable request that khubd sent while it was in the addressed
state, which is why I didn't catch it.
Move the LPM disable before the device reset, so that we can send the
Clear Feature U1/U2 Enable successfully, and balance the LPM disable
count.
Also delete any calls to usb_enable_lpm() on error paths that lead to
re-enumeration. The calls will fail because the device isn't
configured, and it's not useful to balance the LPM disable count because
the usb_device is about to be destroyed before re-enumeration.
Fix the early exit path ("done" label) to call usb_enable_lpm() to
balance the LPM disable count.
Note that calling usb_reset_and_verify_device() with an unconfigured
device may fail on the first call to usb_disable_lpm(). That's because
the LPM disable count is initialized to 0 (LPM enabled), and
usb_disable_lpm() will attempt to send a Clear Feature U1/U2 request to
a device in the Addressed state. The next patch will fix that.
This commit should be backported to kernels as old as 3.5, that contain
the commit
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| atm | ||
| c67x00 | ||
| chipidea | ||
| class | ||
| core | ||
| dwc3 | ||
| early | ||
| gadget | ||
| host | ||
| image | ||
| misc | ||
| mon | ||
| musb | ||
| otg | ||
| phy | ||
| 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.