diff options
Diffstat (limited to 'drivers/usb/serial/pl2303.c')
-rw-r--r-- | drivers/usb/serial/pl2303.c | 34 |
1 files changed, 25 insertions, 9 deletions
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c index 1e3318d..beb8edc 100644 --- a/drivers/usb/serial/pl2303.c +++ b/drivers/usb/serial/pl2303.c @@ -142,6 +142,8 @@ struct pl2303_private { spinlock_t lock; u8 line_control; u8 line_status; + + u8 line_settings[7]; }; static int pl2303_vendor_read(__u16 value, __u16 index, @@ -339,11 +341,6 @@ static void pl2303_set_termios(struct tty_struct *tty, int i; u8 control; - /* - * The PL2303 is reported to lose bytes if you change serial settings - * even to the same values as before. Thus we actually need to filter - * in this specific case. - */ if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios)) return; @@ -428,10 +425,29 @@ static void pl2303_set_termios(struct tty_struct *tty, dev_dbg(&port->dev, "parity = none\n"); } - i = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0), - SET_LINE_REQUEST, SET_LINE_REQUEST_TYPE, - 0, 0, buf, 7, 100); - dev_dbg(&port->dev, "0x21:0x20:0:0 %d\n", i); + /* + * Some PL2303 are known to lose bytes if you change serial settings + * even to the same values as before. Thus we actually need to filter + * in this specific case. + * + * Note that the tty_termios_hw_change check above is not sufficient + * as a previously requested baud rate may differ from the one + * actually used (and stored in old_termios). + * + * NOTE: No additional locking needed for line_settings as it is + * only used in set_termios, which is serialised against itself. + */ + if (!old_termios || memcmp(buf, priv->line_settings, 7)) { + i = usb_control_msg(serial->dev, + usb_sndctrlpipe(serial->dev, 0), + SET_LINE_REQUEST, SET_LINE_REQUEST_TYPE, + 0, 0, buf, 7, 100); + + dev_dbg(&port->dev, "0x21:0x20:0:0 %d\n", i); + + if (i == 7) + memcpy(priv->line_settings, buf, 7); + } /* change control lines if we are switching to or from B0 */ spin_lock_irqsave(&priv->lock, flags); |