[PATCH 0/2] Still not applied (resending again)

Alan Cox · External Since: Aug 19, 2009 Posts: 13

Regression fixes for the carrier handling when using O_NDELAY
---

Alan Cox (2):
tty_port: If we are opened non blocking we still need to raise the carrier
cp210x: Fix carrier handling

drivers/char/tty_port.c | 10 ++++++++--
drivers/usb/serial/cp210x.c | 21 +++++++++++++++++++++
2 files changed, 29 insertions(+), 2 deletions(-)

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Alan Cox · External Since: Aug 19, 2009 Posts: 13

The tty_port code inherited a bug common to various drivers it was based
upon. If the tty is opened O_NONBLOCK we do not wait for the carrier to be
raised but we must still raise our modem lines if appropriate.

(There is a second question here about whether we should do so if CLOCAL is
set but that can wait)

Signed-off-by: Alan Cox <alan.RemoveThis@linux.intel.com>
---

drivers/char/tty_port.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 0a35600..5e2ac57 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -241,8 +241,14 @@ int tty_port_block_til_ready(struct tty_port *port,

/* if non-blocking mode is set we can pass directly to open unless
the port has just hung up or is in another error state */
- if ((filp->f_flags & O_NONBLOCK) ||
- (tty->flags & (1 << TTY_IO_ERROR))) {
+ if (tty->flags & (1 << TTY_IO_ERROR)) {
+ port->flags |= ASYNC_NORMAL_ACTIVE;
+ return 0;
+ }
+ if (filp->f_flags & O_NONBLOCK) {
+ /* Indicate we are open */
+ if (tty->termios->c_cflag & CBAUD)
+ tty_port_raise_dtr_rts(port);
port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}

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Alan Cox · External Since: Aug 19, 2009 Posts: 13

9a68e39d4a701fb3be03cae9b462408664ebd205 broke carrier handling so that a
cp210x setup which needed the carrier lines set up (non CLOCAL) which did
not make a call which set the termios bits left the lines down even if
CLOCAL was not asserted.

Fix this not by reverting but by adding the proper dtr_rts and
carrier_raised methods. This both sets the modem lines properly and also
implements the correct blocking semantics for the port as required by
POSIX.

Signed-off-by: Alan Cox <alan.TakeThisOut@linux.intel.com>
---

drivers/usb/serial/cp210x.c | 21 +++++++++++++++++++++
1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 698252a..bd254ec 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -50,6 +50,8 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *,
static void cp210x_break_ctl(struct tty_struct *, int);
static int cp210x_startup(struct usb_serial *);
static void cp210x_disconnect(struct usb_serial *);
+static void cp210x_dtr_rts(struct usb_serial_port *p, int on);
+static int cp210x_carrier_raised(struct usb_serial_port *p);

static int debug;

@@ -143,6 +145,8 @@ static struct usb_serial_driver cp210x_device = {
.tiocmset = cp210x_tiocmset,
.attach = cp210x_startup,
.disconnect = cp210x_disconnect,
+ .dtr_rts = cp210x_dtr_rts,
+ .carrier_raised = cp210x_carrier_raised
};

/* Config request types */
@@ -746,6 +750,14 @@ static int cp210x_tiocmset_port(struct usb_serial_port *port, struct file *file,
return cp210x_set_config(port, CP210X_SET_MHS, &control, 2);
}

+static void cp210x_dtr_rts(struct usb_serial_port *p, int on)
+{
+ if (on)
+ cp210x_tiocmset_port(p, NULL, TIOCM_DTR|TIOCM_RTS, 0);
+ else
+ cp210x_tiocmset_port(p, NULL, 0, TIOCM_DTR|TIOCM_RTS);
+}
+
static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
{
struct usb_serial_port *port = tty->driver_data;
@@ -768,6 +780,15 @@ static int cp210x_tiocmget (struct tty_struct *tty, struct file *file)
return result;
}

+static int cp210x_carrier_raised(struct usb_serial_port *p)
+{
+ unsigned int control;
+ cp210x_get_config(p, CP210X_GET_MDMSTS, &control, 1);
+ if (control & CONTROL_DCD)
+ return 1;
+ return 0;
+}
+
static void cp210x_break_ctl (struct tty_struct *tty, int break_state)
{
struct usb_serial_port *port = tty->driver_data;

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Greg KH · External Since: Nov 18, 2004 Posts: 1094

On Fri, Nov 06, 2009 at 11:32:29AM +0000, Alan Cox wrote:
> Regression fixes for the carrier handling when using O_NDELAY

I added these to my tree yesterday, sorry for the delay.

greg k-h
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