kernel/linux.git/drivers/usb/serial/generic.c, branch linux-2.6.35.y

USB: serial: handle Data Carrier Detect changes

2011-03-31T18:57:38+00:00

commit d14fc1a74e846d7851f24fc9519fe87dc12a1231 upstream. 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Andi Kleen

USB: serial: fix stalled writes

2010-08-13T20:31:01+00:00

commit b58af4066d240b18b43f202e07b9ec7461d90b17 upstream. As David VomLehn points out, it was possible to receive an interrupt before clearing the free-urb flag which could lead to the urb being incorrectly marked as busy. For the same reason, move tx_bytes accounting so that it will never be negative. Note that the free-flags set and clear operations do not need any additional locking as they are manipulated while USB_SERIAL_WRITE_BUSY is set. Reported-by: David VomLehn Tested-by: David VomLehn Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: add special case for processing of empty read urbs

2010-05-20T20:21:48+00:00

Return immediately from generic process_read_urb if urb is empty. Signed-off-by: Johan Hovold 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: allow custom multi-urb write bulk callbacks

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

Allow drivers to implement their own multi-urb write bulk callbacks as we do for single urb writes. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: clean up generic write start busy test

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

Submit write urb if it is not already in use and we have buffered data. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: clean up some error and debug messages in generic driver

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

Clean up error messages on usb_submit_urb failure. Remove debug message on zero-length writes. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman