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Subject[patch 1/1] 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>

Index: linux-staging/drivers/staging/speakup/serialio.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/serialio.c
+++ linux-staging/drivers/staging/speakup/serialio.c
@@ -30,6 +30,7 @@
static void spk_serial_tiocmset(unsigned int set, unsigned int clear);
static unsigned char spk_serial_in(void);
static unsigned char spk_serial_in_nowait(void);
+static void spk_serial_flush_buffer(void);

struct spk_io_ops spk_serial_io_ops = {
.synth_out = spk_serial_out,
@@ -37,6 +38,7 @@
.tiocmset = spk_serial_tiocmset,
.synth_in = spk_serial_in,
.synth_in_nowait = spk_serial_in_nowait,
+ .flush_buffer = spk_serial_flush_buffer,
};
EXPORT_SYMBOL_GPL(spk_serial_io_ops);

@@ -268,6 +270,11 @@
return inb_p(speakup_info.port_tts + UART_RX);
}

+static void spk_serial_flush_buffer(void)
+{
+ /* TODO: flush the UART 16550 buffer */
+}
+
static int spk_serial_out(struct spk_synth *in_synth, const char ch)
{
if (in_synth->alive && spk_wait_for_xmitr(in_synth)) {
Index: linux-staging/drivers/staging/speakup/spk_ttyio.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/spk_ttyio.c
+++ linux-staging/drivers/staging/speakup/spk_ttyio.c
@@ -85,6 +85,7 @@
static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear);
static unsigned char spk_ttyio_in(void);
static unsigned char spk_ttyio_in_nowait(void);
+static void spk_ttyio_flush_buffer(void);

struct spk_io_ops spk_ttyio_ops = {
.synth_out = spk_ttyio_out,
@@ -92,6 +93,7 @@
.tiocmset = spk_ttyio_tiocmset,
.synth_in = spk_ttyio_in,
.synth_in_nowait = spk_ttyio_in_nowait,
+ .flush_buffer = spk_ttyio_flush_buffer,
};
EXPORT_SYMBOL_GPL(spk_ttyio_ops);

@@ -99,6 +101,7 @@
{
int ret = 0;
struct tty_struct *tty;
+ struct ktermios tmp_termios;

ret = tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops);
if (ret) {
@@ -127,6 +130,18 @@
}

clear_bit(TTY_HUPPED, &tty->flags);
+ /* ensure hardware flow control is enabled */
+ down_read(&tty->termios_rwsem);
+ tmp_termios = tty->termios;
+ up_read(&tty->termios_rwsem);
+
+ if (!(tmp_termios.c_cflag & CRTSCTS)) {
+ tmp_termios.c_cflag |= CRTSCTS;
+ ret = tty_set_termios(tty, &tmp_termios);
+ if (ret)
+ pr_warn("speakup: Failed to set hardware flow control\n");
+ }
+
tty_unlock(tty);

ret = tty_set_ldisc(tty, N_SPEAKUP);
@@ -201,6 +216,11 @@
return (rv == 0xff) ? 0 : rv;
}

+static void spk_ttyio_flush_buffer(void)
+{
+ speakup_tty->ops->flush_buffer(speakup_tty);
+}
+
int spk_ttyio_synth_probe(struct spk_synth *synth)
{
int rv = spk_ttyio_initialise_ldisc(synth->ser);
Index: linux-staging/drivers/staging/speakup/spk_types.h
===================================================================
--- linux-staging.orig/drivers/staging/speakup/spk_types.h
+++ linux-staging/drivers/staging/speakup/spk_types.h
@@ -154,6 +154,7 @@
void (*tiocmset)(unsigned int set, unsigned int clear);
unsigned char (*synth_in)(void);
unsigned char (*synth_in_nowait)(void);
+ void (*flush_buffer)(void);
};

struct spk_synth {
Index: linux-staging/drivers/staging/speakup/speakup_audptr.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_audptr.c
+++ linux-staging/drivers/staging/speakup/speakup_audptr.c
@@ -127,6 +127,7 @@

static void synth_flush(struct spk_synth *synth)
{
+ synth->io_ops->flush_buffer();
synth->io_ops->send_xchar(SYNTH_CLEAR);
synth->io_ops->synth_out(synth, PROCSPEECH);
}
Index: linux-staging/drivers/staging/speakup/speakup_decext.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_decext.c
+++ linux-staging/drivers/staging/speakup/speakup_decext.c
@@ -221,6 +221,7 @@
static void synth_flush(struct spk_synth *synth)
{
in_escape = 0;
+ synth->io_ops->flush_buffer();
synth->synth_immediate(synth, "\033P;10z\033\\");
}

Index: linux-staging/drivers/staging/speakup/speakup_dectlk.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_dectlk.c
+++ linux-staging/drivers/staging/speakup/speakup_dectlk.c
@@ -293,6 +293,7 @@
synth->io_ops->synth_out(synth, ']');
in_escape = 0;
is_flushing = 1;
+ synth->io_ops->flush_buffer();
synth->io_ops->synth_out(synth, SYNTH_CLEAR);
}

Index: linux-staging/drivers/staging/speakup/speakup_spkout.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_spkout.c
+++ linux-staging/drivers/staging/speakup/speakup_spkout.c
@@ -125,6 +125,7 @@

static void synth_flush(struct spk_synth *synth)
{
+ synth->io_ops->flush_buffer();
synth->io_ops->send_xchar(SYNTH_CLEAR);
}

Index: linux-staging/drivers/staging/speakup/synth.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/synth.c
+++ linux-staging/drivers/staging/speakup/synth.c
@@ -120,6 +120,7 @@

void spk_synth_flush(struct spk_synth *synth)
{
+ synth->io_ops->flush_buffer();
synth->io_ops->synth_out(synth, synth->clear);
}
EXPORT_SYMBOL_GPL(spk_synth_flush);
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