2.6.27-stable review patch. If anyone has any objections, please let us know. ------------------ From: Oliver Neukum commit 2400a2bfbd0e912193fe3b077f492d4980141813 upstream [ cebbert@redhat.com: backport to 2.6.27 ] USB: removal of tty->low_latency hack dating back to the old serial code This removes tty->low_latency from all USB serial drivers that push data into the tty layer at hard interrupt context. It's no longer needed and actually harmful. Signed-off-by: Oliver Neukum Cc: Alan Cox Cc: Chuck Ebbert Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/cyberjack.c | 7 ------- drivers/usb/serial/cypress_m8.c | 4 ---- drivers/usb/serial/empeg.c | 6 ------ drivers/usb/serial/garmin_gps.c | 8 -------- drivers/usb/serial/generic.c | 6 ------ drivers/usb/serial/io_edgeport.c | 8 -------- drivers/usb/serial/io_ti.c | 8 -------- drivers/usb/serial/ipaq.c | 6 ------ drivers/usb/serial/ipw.c | 3 --- drivers/usb/serial/iuu_phoenix.c | 1 - drivers/usb/serial/kobil_sct.c | 6 ------ drivers/usb/serial/mos7720.c | 7 ------- drivers/usb/serial/mos7840.c | 6 ------ drivers/usb/serial/option.c | 3 --- drivers/usb/serial/sierra.c | 3 --- drivers/usb/serial/ti_usb_3410_5052.c | 17 +---------------- drivers/usb/serial/visor.c | 8 -------- 17 files changed, 1 insertion(+), 106 deletions(-) --- a/drivers/usb/serial/cyberjack.c +++ b/drivers/usb/serial/cyberjack.c @@ -174,13 +174,6 @@ static int cyberjack_open(struct tty_st dbg("%s - usb_clear_halt", __func__); usb_clear_halt(port->serial->dev, port->write_urb->pipe); - /* force low_latency on so that our tty_push actually forces - * the data through, otherwise it is scheduled, and with high - * data rates (like with OHCI) data can get lost. - */ - if (tty) - tty->low_latency = 1; - priv = usb_get_serial_port_data(port); spin_lock_irqsave(&priv->lock, flags); priv->rdtodo = 0; --- a/drivers/usb/serial/cypress_m8.c +++ b/drivers/usb/serial/cypress_m8.c @@ -655,10 +655,6 @@ static int cypress_open(struct tty_struc priv->rx_flags = 0; spin_unlock_irqrestore(&priv->lock, flags); - /* setting to zero could cause data loss */ - if (tty) - tty->low_latency = 1; - /* raise both lines and set termios */ spin_lock_irqsave(&priv->lock, flags); priv->line_control = CONTROL_DTR | CONTROL_RTS; --- a/drivers/usb/serial/empeg.c +++ b/drivers/usb/serial/empeg.c @@ -478,12 +478,6 @@ static void empeg_set_termios(struct tty termios->c_cflag |= CS8; /* character size 8 bits */ - /* - * Force low_latency on; otherwise the pushes are scheduled; - * this is bad as it opens up the possibility of dropping bytes - * on the floor. We don't want to drop bytes on the floor. :) - */ - tty->low_latency = 1; tty_encode_baud_rate(tty, 115200, 115200); } --- a/drivers/usb/serial/garmin_gps.c +++ b/drivers/usb/serial/garmin_gps.c @@ -972,14 +972,6 @@ static int garmin_open(struct tty_struct dbg("%s - port %d", __func__, port->number); - /* - * Force low_latency on so that our tty_push actually forces the data - * through, otherwise it is scheduled, and with high data rates (like - * with OHCI) data can get lost. - */ - if (tty) - tty->low_latency = 1; - spin_lock_irqsave(&garmin_data_p->lock, flags); garmin_data_p->mode = initial_mode; garmin_data_p->count = 0; --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -122,12 +122,6 @@ int usb_serial_generic_open(struct tty_s dbg("%s - port %d", __func__, port->number); - /* force low_latency on so that our tty_push actually forces the data - through, otherwise it is scheduled, and with high data rates (like - with OHCI) data can get lost. */ - if (tty) - tty->low_latency = 1; - /* clear the throttle flags */ spin_lock_irqsave(&port->lock, flags); port->throttled = 0; --- a/drivers/usb/serial/io_edgeport.c +++ b/drivers/usb/serial/io_edgeport.c @@ -193,8 +193,6 @@ static const struct divisor_table_entry /* local variables */ static int debug; -static int low_latency = 1; /* tty low latency flag, on by default */ - static atomic_t CmdUrbs; /* Number of outstanding Command Write Urbs */ @@ -861,9 +859,6 @@ static int edge_open(struct tty_struct * if (edge_port == NULL) return -ENODEV; - if (tty) - tty->low_latency = low_latency; - /* see if we've set up our endpoint info yet (can't set it up in edge_startup as the structures were not set up at that time.) */ serial = port->serial; @@ -3281,6 +3276,3 @@ MODULE_FIRMWARE("edgeport/down2.fw"); module_param(debug, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(debug, "Debug enabled or not"); - -module_param(low_latency, bool, S_IRUGO | S_IWUSR); -MODULE_PARM_DESC(low_latency, "Low latency enabled or not"); --- a/drivers/usb/serial/io_ti.c +++ b/drivers/usb/serial/io_ti.c @@ -76,7 +76,6 @@ struct edgeport_uart_buf_desc { #define EDGE_READ_URB_STOPPING 1 #define EDGE_READ_URB_STOPPED 2 -#define EDGE_LOW_LATENCY 1 #define EDGE_CLOSING_WAIT 4000 /* in .01 sec */ #define EDGE_OUT_BUF_SIZE 1024 @@ -232,7 +231,6 @@ static unsigned short OperationalBuildNu static int debug; -static int low_latency = EDGE_LOW_LATENCY; static int closing_wait = EDGE_CLOSING_WAIT; static int ignore_cpu_rev; static int default_uart_mode; /* RS232 */ @@ -1838,9 +1836,6 @@ static int edge_open(struct tty_struct * if (edge_port == NULL) return -ENODEV; - if (tty) - tty->low_latency = low_latency; - port_number = port->number - port->serial->minor; switch (port_number) { case 0: @@ -2995,9 +2990,6 @@ MODULE_FIRMWARE("edgeport/down3.bin"); module_param(debug, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(debug, "Debug enabled or not"); -module_param(low_latency, bool, S_IRUGO | S_IWUSR); -MODULE_PARM_DESC(low_latency, "Low latency enabled or not"); - module_param(closing_wait, int, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(closing_wait, "Maximum wait for data to drain, in .01 secs"); --- a/drivers/usb/serial/ipaq.c +++ b/drivers/usb/serial/ipaq.c @@ -635,13 +635,7 @@ static int ipaq_open(struct tty_struct * priv->free_len += PACKET_SIZE; } - /* - * Force low latency on. This will immediately push data to the line - * discipline instead of queueing. - */ - if (tty) { - tty->low_latency = 1; /* FIXME: These two are bogus */ tty->raw = 1; tty->real_raw = 1; --- a/drivers/usb/serial/ipw.c +++ b/drivers/usb/serial/ipw.c @@ -206,9 +206,6 @@ static int ipw_open(struct tty_struct *t if (!buf_flow_init) return -ENOMEM; - if (tty) - tty->low_latency = 1; - /* --1: Tell the modem to initialize (we think) From sniffs this is * always the first thing that gets sent to the modem during * opening of the device */ --- a/drivers/usb/serial/iuu_phoenix.c +++ b/drivers/usb/serial/iuu_phoenix.c @@ -1046,7 +1046,6 @@ static int iuu_open(struct tty_struct *t tty->termios->c_oflag = 0; tty->termios->c_iflag = 0; priv->termios_initialized = 1; - tty->low_latency = 1; priv->poll = 0; } spin_unlock_irqrestore(&priv->lock, flags); --- a/drivers/usb/serial/kobil_sct.c +++ b/drivers/usb/serial/kobil_sct.c @@ -231,13 +231,7 @@ static int kobil_open(struct tty_struct /* someone sets the dev to 0 if the close method has been called */ port->interrupt_in_urb->dev = port->serial->dev; - - /* force low_latency on so that our tty_push actually forces - * the data through, otherwise it is scheduled, and with high - * data rates (like with OHCI) data can get lost. - */ if (tty) { - tty->low_latency = 1; /* Default to echo off and other sane device settings */ tty->termios->c_lflag = 0; --- a/drivers/usb/serial/mos7720.c +++ b/drivers/usb/serial/mos7720.c @@ -442,13 +442,6 @@ static int mos7720_open(struct tty_struc data = 0x0c; send_mos_cmd(serial, MOS_WRITE, port_number, 0x01, &data); - /* force low_latency on so that our tty_push actually forces * - * the data through,otherwise it is scheduled, and with * - * high data rates (like with OHCI) data can get lost. */ - - if (tty) - tty->low_latency = 1; - /* see if we've set up our endpoint info yet * * (can't set it up in mos7720_startup as the * * structures were not set up at that time.) */ --- a/drivers/usb/serial/mos7840.c +++ b/drivers/usb/serial/mos7840.c @@ -990,12 +990,6 @@ static int mos7840_open(struct tty_struc status = mos7840_set_reg_sync(port, mos7840_port->ControlRegOffset, Data); - /* force low_latency on so that our tty_push actually forces * - * the data through,otherwise it is scheduled, and with * - * high data rates (like with OHCI) data can get lost. */ - if (tty) - tty->low_latency = 1; - /* Check to see if we've set up our endpoint info yet * * (can't set it up in mos7840_startup as the structures * * were not set up at that time.) */ --- a/drivers/usb/serial/option.c +++ b/drivers/usb/serial/option.c @@ -914,9 +914,6 @@ static int option_open(struct tty_struct usb_pipeout(urb->pipe), 0); */ } - if (tty) - tty->low_latency = 1; - option_send_setup(tty, port); return 0; --- a/drivers/usb/serial/sierra.c +++ b/drivers/usb/serial/sierra.c @@ -576,9 +576,6 @@ static int sierra_open(struct tty_struct } } - if (tty) - tty->low_latency = 1; - sierra_send_setup(tty, port); /* start up the interrupt endpoint if we have one */ --- a/drivers/usb/serial/ti_usb_3410_5052.c +++ b/drivers/usb/serial/ti_usb_3410_5052.c @@ -101,11 +101,10 @@ #define TI_TRANSFER_TIMEOUT 2 -#define TI_DEFAULT_LOW_LATENCY 0 #define TI_DEFAULT_CLOSING_WAIT 4000 /* in .01 secs */ /* supported setserial flags */ -#define TI_SET_SERIAL_FLAGS (ASYNC_LOW_LATENCY) +#define TI_SET_SERIAL_FLAGS 0 /* read urb states */ #define TI_READ_URB_RUNNING 0 @@ -212,7 +211,6 @@ static int ti_buf_get(struct circ_buf *c /* module parameters */ static int debug; -static int low_latency = TI_DEFAULT_LOW_LATENCY; static int closing_wait = TI_DEFAULT_CLOSING_WAIT; static ushort vendor_3410[TI_EXTRA_VID_PID_COUNT]; static unsigned int vendor_3410_count; @@ -333,10 +331,6 @@ MODULE_FIRMWARE("ti_5052.fw"); module_param(debug, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(debug, "Enable debugging, 0=no, 1=yes"); -module_param(low_latency, bool, S_IRUGO | S_IWUSR); -MODULE_PARM_DESC(low_latency, - "TTY low_latency flag, 0=off, 1=on, default is off"); - module_param(closing_wait, int, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(closing_wait, "Maximum wait for data to drain in close, in .01 secs, default is 4000"); @@ -480,7 +474,6 @@ static int ti_startup(struct usb_serial spin_lock_init(&tport->tp_lock); tport->tp_uart_base_addr = (i == 0 ? TI_UART1_BASE_ADDR : TI_UART2_BASE_ADDR); - tport->tp_flags = low_latency ? ASYNC_LOW_LATENCY : 0; tport->tp_closing_wait = closing_wait; init_waitqueue_head(&tport->tp_msr_wait); init_waitqueue_head(&tport->tp_write_wait); @@ -560,10 +553,6 @@ static int ti_open(struct tty_struct *tt if (mutex_lock_interruptible(&tdev->td_open_close_lock)) return -ERESTARTSYS; - if (tty) - tty->low_latency = - (tport->tp_flags & ASYNC_LOW_LATENCY) ? 1 : 0; - port_number = port->number - port->serial->minor; memset(&(tport->tp_icount), 0x00, sizeof(tport->tp_icount)); @@ -1480,10 +1469,6 @@ static int ti_set_serial_info(struct ti_ return -EFAULT; tport->tp_flags = new_serial.flags & TI_SET_SERIAL_FLAGS; - /* FIXME */ - if (port->port.tty) - port->port.tty->low_latency = - (tport->tp_flags & ASYNC_LOW_LATENCY) ? 1 : 0; tport->tp_closing_wait = new_serial.closing_wait; return 0; --- a/drivers/usb/serial/visor.c +++ b/drivers/usb/serial/visor.c @@ -296,14 +296,6 @@ static int visor_open(struct tty_struct priv->throttled = 0; spin_unlock_irqrestore(&priv->lock, flags); - /* - * Force low_latency on so that our tty_push actually forces the data - * through, otherwise it is scheduled, and with high data rates (like - * with OHCI) data can get lost. - */ - if (tty) - tty->low_latency = 1; - /* Start reading from the device */ usb_fill_bulk_urb(port->read_urb, serial->dev, usb_rcvbulkpipe(serial->dev, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/