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876ae50d94
There are two issues here, one is that the device is generating spurious very fast modem status line changes somewhere: CTS becomes high then low 18µs later: [121226.924373] ftdi_process_packet: prev rng=0 dsr=10 dcd=0 cts=6 [121226.924378] ftdi_process_packet: status=10 prev=00 diff=10 [121226.924382] ftdi_process_packet: now rng=0 dsr=10 dcd=0 cts=7 (wake_up_interruptible is called) [121226.924391] ftdi_process_packet: prev rng=0 dsr=10 dcd=0 cts=7 [121226.924394] ftdi_process_packet: status=00 prev=10 diff=10 [121226.924397] ftdi_process_packet: now rng=0 dsr=10 dcd=0 cts=8 (wake_up_interruptible is called) This wakes up the task in TIOCMIWAIT: [121226.924405] ftdi_ioctl: 19451 rng=0->0 dsr=10->10 dcd=0->0 cts=6->8 (wait from 20:51:46 returns and observes both changes) Which then calls TIOCMIWAIT again: 20:51:46.400239 ioctl(3, TIOCMIWAIT, 0x20) = 0 22:11:09.441818 ioctl(3, TIOCMGET, [TIOCM_DTR|TIOCM_RTS]) = 0 22:11:09.442812 ioctl(3, TIOCMIWAIT, 0x20) = -1 EIO (Input/output error) (the second wake_up_interruptible takes effect and an I/O error occurs) The other issue is that TIOCMIWAIT will wait forever (unless the task is interrupted) if the device is removed. This change removes the -EIO return that occurs if the counts don't appear to have changed. Multiple counts may have been processed as one or the waiting task may have started waiting after recording the current count. It adds a bool to indicate that the device has been removed so that TIOCMIWAIT doesn't wait forever, and wakes up any tasks so that they can return -EIO. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| atm | ||
| c67x00 | ||
| class | ||
| core | ||
| 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.