diff options
| -rw-r--r-- | drivers/char/tty_ioctl.c | 45 |
1 files changed, 30 insertions, 15 deletions
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c index dee47f40c6a3..fd471cb3338f 100644 --- a/drivers/char/tty_ioctl.c +++ b/drivers/char/tty_ioctl.c @@ -225,7 +225,7 @@ EXPORT_SYMBOL(tty_termios_input_baud_rate); /** * tty_termios_encode_baud_rate - * @termios: termios structure + * @termios: ktermios structure holding user requested state * @ispeed: input speed * @ospeed: output speed * @@ -233,7 +233,10 @@ EXPORT_SYMBOL(tty_termios_input_baud_rate); * used as a library helper for drivers os that they can report back * the actual speed selected when it differs from the speed requested * - * For now input and output speed must agree. + * For maximal back compatibility with legacy SYS5/POSIX *nix behaviour + * we need to carefully set the bits when the user does not get the + * desired speed. We allow small margins and preserve as much of possible + * of the input intent to keep compatiblity. * * Locking: Caller should hold termios lock. This is already held * when calling this function from the driver termios handler. @@ -242,32 +245,44 @@ EXPORT_SYMBOL(tty_termios_input_baud_rate); void tty_termios_encode_baud_rate(struct ktermios *termios, speed_t ibaud, speed_t obaud) { int i = 0; - int ifound = 0, ofound = 0; + int ifound = -1, ofound = -1; + int iclose = ibaud/50, oclose = obaud/50; + int ibinput = 0; termios->c_ispeed = ibaud; termios->c_ospeed = obaud; + /* If the user asked for a precise weird speed give a precise weird + answer. If they asked for a Bfoo speed they many have problems + digesting non-exact replies so fuzz a bit */ + + if ((termios->c_cflag & CBAUD) == BOTHER) + oclose = 0; + if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER) + iclose = 0; + if ((termios->c_cflag >> IBSHIFT) & CBAUD) + ibinput = 1; /* An input speed was specified */ + termios->c_cflag &= ~CBAUD; - /* Identical speed means no input encoding (ie B0 << IBSHIFT)*/ - if (termios->c_ispeed == termios->c_ospeed) - ifound = 1; do { - if (obaud == baud_table[i]) { + if (obaud - oclose >= baud_table[i] && obaud + oclose <= baud_table[i]) { termios->c_cflag |= baud_bits[i]; - ofound = 1; - /* So that if ibaud == obaud we don't set it */ - continue; + ofound = i; } - if (ibaud == baud_table[i]) { - termios->c_cflag |= (baud_bits[i] << IBSHIFT); - ifound = 1; + if (ibaud - iclose >= baud_table[i] && ibaud + iclose <= baud_table[i]) { + /* For the case input == output don't set IBAUD bits if the user didn't do so */ + if (ofound != i || ibinput) + termios->c_cflag |= (baud_bits[i] << IBSHIFT); + ifound = i; } } while(++i < n_baud_table); - if (!ofound) + if (ofound == -1) termios->c_cflag |= BOTHER; - if (!ifound) + /* Set exact input bits only if the input and output differ or the + user already did */ + if (ifound == -1 && (ibaud != obaud || ibinput)) termios->c_cflag |= (BOTHER << IBSHIFT); } |