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staging: speakup: flush tty buffers and ensure hardware flow control
This patch fixes the issue where TTY-migrated synths would take a while to shut up after hitting numpad enter key. When calling synth_flush, even though XOFF character is sent as high priority, data buffered in TTY layer is still sent to the synth. This patch flushes that buffered data when synth_flush is called. It also tries to ensure that hardware flow control is enabled, by setting CRTSCTS using tty's termios. Reported-by: John Covici <covici@ccs.covici.com> Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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8 changed files with 42 additions and 0 deletions
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@ -30,6 +30,7 @@ static void spk_serial_send_xchar(char ch);
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static void spk_serial_tiocmset(unsigned int set, unsigned int clear);
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static unsigned char spk_serial_in(void);
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static unsigned char spk_serial_in_nowait(void);
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static void spk_serial_flush_buffer(void);
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struct spk_io_ops spk_serial_io_ops = {
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.synth_out = spk_serial_out,
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@ -37,6 +38,7 @@ struct spk_io_ops spk_serial_io_ops = {
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.tiocmset = spk_serial_tiocmset,
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.synth_in = spk_serial_in,
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.synth_in_nowait = spk_serial_in_nowait,
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.flush_buffer = spk_serial_flush_buffer,
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};
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EXPORT_SYMBOL_GPL(spk_serial_io_ops);
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@ -268,6 +270,11 @@ static unsigned char spk_serial_in_nowait(void)
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return inb_p(speakup_info.port_tts + UART_RX);
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}
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static void spk_serial_flush_buffer(void)
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{
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/* TODO: flush the UART 16550 buffer */
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}
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static int spk_serial_out(struct spk_synth *in_synth, const char ch)
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{
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if (in_synth->alive && spk_wait_for_xmitr(in_synth)) {
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@ -127,6 +127,7 @@ static struct spk_synth synth_audptr = {
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static void synth_flush(struct spk_synth *synth)
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{
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synth->io_ops->flush_buffer();
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synth->io_ops->send_xchar(SYNTH_CLEAR);
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synth->io_ops->synth_out(synth, PROCSPEECH);
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}
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@ -221,6 +221,7 @@ static void do_catch_up(struct spk_synth *synth)
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static void synth_flush(struct spk_synth *synth)
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{
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in_escape = 0;
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synth->io_ops->flush_buffer();
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synth->synth_immediate(synth, "\033P;10z\033\\");
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}
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@ -293,6 +293,7 @@ static void synth_flush(struct spk_synth *synth)
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synth->io_ops->synth_out(synth, ']');
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in_escape = 0;
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is_flushing = 1;
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synth->io_ops->flush_buffer();
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synth->io_ops->synth_out(synth, SYNTH_CLEAR);
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}
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@ -125,6 +125,7 @@ static struct spk_synth synth_spkout = {
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static void synth_flush(struct spk_synth *synth)
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{
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synth->io_ops->flush_buffer();
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synth->io_ops->send_xchar(SYNTH_CLEAR);
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}
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@ -85,6 +85,7 @@ static void spk_ttyio_send_xchar(char ch);
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static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear);
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static unsigned char spk_ttyio_in(void);
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static unsigned char spk_ttyio_in_nowait(void);
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static void spk_ttyio_flush_buffer(void);
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struct spk_io_ops spk_ttyio_ops = {
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.synth_out = spk_ttyio_out,
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@ -92,13 +93,22 @@ struct spk_io_ops spk_ttyio_ops = {
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.tiocmset = spk_ttyio_tiocmset,
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.synth_in = spk_ttyio_in,
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.synth_in_nowait = spk_ttyio_in_nowait,
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.flush_buffer = spk_ttyio_flush_buffer,
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};
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EXPORT_SYMBOL_GPL(spk_ttyio_ops);
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static inline void get_termios(struct tty_struct *tty, struct ktermios *out_termios)
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{
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down_read(&tty->termios_rwsem);
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*out_termios = tty->termios;
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up_read(&tty->termios_rwsem);
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}
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static int spk_ttyio_initialise_ldisc(int ser)
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{
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int ret = 0;
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struct tty_struct *tty;
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struct ktermios tmp_termios;
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ret = tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops);
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if (ret) {
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@ -127,6 +137,20 @@ static int spk_ttyio_initialise_ldisc(int ser)
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}
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clear_bit(TTY_HUPPED, &tty->flags);
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/* ensure hardware flow control is enabled */
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get_termios(tty, &tmp_termios);
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if (!(tmp_termios.c_cflag & CRTSCTS)) {
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tmp_termios.c_cflag |= CRTSCTS;
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tty_set_termios(tty, &tmp_termios);
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/*
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* check c_cflag to see if it's updated as tty_set_termios may not return
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* error even when no tty bits are changed by the request.
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*/
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get_termios(tty, &tmp_termios);
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if (!(tmp_termios.c_cflag & CRTSCTS))
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pr_warn("speakup: Failed to set hardware flow control\n");
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}
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tty_unlock(tty);
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ret = tty_set_ldisc(tty, N_SPEAKUP);
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@ -201,6 +225,11 @@ static unsigned char spk_ttyio_in_nowait(void)
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return (rv == 0xff) ? 0 : rv;
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}
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static void spk_ttyio_flush_buffer(void)
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{
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speakup_tty->ops->flush_buffer(speakup_tty);
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}
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int spk_ttyio_synth_probe(struct spk_synth *synth)
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{
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int rv = spk_ttyio_initialise_ldisc(synth->ser);
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@ -154,6 +154,7 @@ struct spk_io_ops {
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void (*tiocmset)(unsigned int set, unsigned int clear);
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unsigned char (*synth_in)(void);
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unsigned char (*synth_in_nowait)(void);
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void (*flush_buffer)(void);
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};
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struct spk_synth {
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@ -120,6 +120,7 @@ EXPORT_SYMBOL_GPL(spk_do_catch_up);
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void spk_synth_flush(struct spk_synth *synth)
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{
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synth->io_ops->flush_buffer();
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synth->io_ops->synth_out(synth, synth->clear);
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}
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EXPORT_SYMBOL_GPL(spk_synth_flush);
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