linux-toradex.git/include/linux/usb/serial.h, branch v2.6.38.6

USB: serial drivers need to use larger bulk-in buffers

2011-03-23T20:03:46+00:00

commit 969e3033ae7733a0af8f7742ca74cd16c0857e71 upstream.

When a driver doesn't know how much data a device is going to send,
the buffer size should be at least as big as the endpoint's maxpacket
value.  The serial drivers don't follow this rule; many of them
request only 256-byte bulk-in buffers.  As a result, they suffer
overflow errors if a high-speed device wants to send a lot of data,
because high-speed bulk endpoints are required to have a maxpacket
size of 512.

This patch (as1450) fixes the problem by using the driver's
bulk_in_size value as a minimum, always allocating buffers no smaller
than the endpoint's maxpacket size.

Signed-off-by: Alan Stern 
Tested-by: Flynn Marquardt 
Signed-off-by: Greg Kroah-Hartman

USB: serial: handle Data Carrier Detect changes

2011-01-23T02:53:26+00:00

Alan's commit 335f8514f200e63d689113d29cb7253a5c282967 introduced
.carrier_raised function in several drivers.  That also means
tty_port_block_til_ready can now suspend the process trying to open the serial
port when Carrier Detect is low and put it into tty_port.open_wait queue.  We
need to wake up the process when Carrier Detect goes high and trigger TTY
hangup when CD goes low.

Some of the devices do not report modem status line changes, or at least we
don't understand the status message, so for those we remove .carrier_raised
again.

Signed-off-by: Libor Pechacek 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: Make tiocgicount a handler

2010-10-22T17:20:04+00:00

Dan Rosenberg noted that various drivers return the struct with uncleared
fields. Instead of spending forever trying to stomp all the drivers that
get it wrong (and every new driver) do the job in one place.

This first patch adds the needed operations and hooks them up, including
the needed USB midlayer and serial core plumbing.

Signed-off-by: Alan Cox 
Signed-off-by: Greg Kroah-Hartman

USB: drop tty argument from usb_serial_handle_sysrq_char()

2010-08-21T07:37:39+00:00

Since handle_sysrq() does not take tty as argument anymore we can
drop it from usb_serial_handle_sysrq_char() as well.

Acked-by: Alan Cox 
Acked-by: Jason Wessel 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Dmitry Torokhov

USB: include/usb/*.h checkpatch cleanup

2010-05-20T20:21:47+00:00

Lots of minor formatting cleanups in includes/usb/ to make checkpatch
happier.

Signed-off-by: Greg Kroah-Hartman

USB: serial: remove multi-urb write from generic driver

2010-05-20T20:21:42+00:00

Remove multi-urb write from the generic driver and simplify the
prepare_write_buffer prototype:

	int (*prepare_write_buffer)(struct usb_serial_port *port,
						void *dest, size_t size);

The default implementation simply fills dest with data from port write
fifo but drivers can override it if they need to process the outgoing
data (e.g. add headers).

Turn ftdi_sio into a generic fifo-based driver, which lowers CPU usage
significantly for small writes while retaining maximum throughput.

Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: serial: reimplement generic fifo-based writes

2010-05-20T20:21:42+00:00

Reimplement fifo-based writes in the generic driver using a multiple
pre-allocated urb scheme.

In contrast to multi-urb writes, no allocations (of urbs or buffers) are
made during run-time and there is less pressure on the host stack
queues as currently only two urbs are used (implementation is generic
and can handle more than two urbs as well, though).

Initial tests using ftdi_sio show that the implementation achieves the
same (maximum) throughput at high baudrates as multi-urb writes. The CPU
usage is much lower than for multi-urb writes for small write requests
and only slightly higher for large (e.g. 2k) requests (due to extra copy
via fifo?).

Also outperforms multi-urb writes for small write requests on an
embedded arm-9 system, where multi-urb writes are CPU-bound at high
baudrates (perf reveals that a lot of time is spent in the host stack
enqueue function -- could perhaps be a bug as well).

Keeping the original write_urb, buffer and flag for now as there are
other drivers depending on them.

Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: serial: generalise write buffer preparation

2010-05-20T20:21:35+00:00

Generalise write buffer preparation.

This allows for drivers to manipulate (e.g. add headers) to bulk out
data before it is sent.

This adds a new function pointer to usb_serial_driver:

int (*prepare_write_buffer)(struct usb_serial_port *port,
		void **dest, size_t size, const void *src, size_t count);

The function is generic and can be used with either kfifo-based or
multi-urb writes:

If *dest is NULL the implementation should allocate dest.
If src is NULL the implementation should use the port write fifo.

If not set, a generic implementation is used which simply uses memcpy or
kfifo_out.

Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: serial: re-implement multi-urb writes in generic driver

2010-05-20T20:21:35+00:00

Use dynamic transfer buffer sizes since it is more efficient to let the
host controller do the partitioning to fit endpoint size. This way we
also do not use more than one urb per write request.

Replace max_in_flight_urbs with multi_urb_write flag in struct
usb_serial_driver to enable multi-urb writes.

Use MAX_TX_URBS=40 and a max buffer size of PAGE_SIZE to prevent DoS
attacks.

Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: serial: generalise generic read implementation

2010-05-20T20:21:34+00:00

Add process_read_urb to usb_serial_driver so that a driver can rely on
the generic read (and throttle) mechanism but still do device specific
processing of incoming data (such as adding tty_flags before pushing to
line discipline).

The default generic implementation handles sysrq for consoles but
otherwise simply pushes to tty.

Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman