aboutsummaryrefslogtreecommitdiff
path: root/hw/serial.c
diff options
context:
space:
mode:
authorAnthony Liguori <aliguori@us.ibm.com>2013-03-05 23:21:33 +0530
committerAnthony Liguori <aliguori@us.ibm.com>2013-03-08 13:57:17 -0600
commitfcfb4d6aae611d1f804d486d3c998000912c4c81 (patch)
tree1821cf5e78f99ae14e5cce17b25e8a039316da1e /hw/serial.c
parent01f45d986fb0b7c2d4f0466efe3cde9708f325be (diff)
serial: add flow control to transmit
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com> Signed-off-by: Amit Shah <amit.shah@redhat.com> Message-id: 2976f10d4e66ed4a34011f6f0d6937026d22be5f.1362505276.git.amit.shah@redhat.com Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'hw/serial.c')
-rw-r--r--hw/serial.c28
1 files changed, 11 insertions, 17 deletions
diff --git a/hw/serial.c b/hw/serial.c
index f0ce9b0c15..eb38f2231d 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -256,16 +256,17 @@ static void serial_update_msl(SerialState *s)
qemu_mod_timer(s->modem_status_poll, qemu_get_clock_ns(vm_clock) + get_ticks_per_sec() / 100);
}
-static void serial_xmit(void *opaque)
+static gboolean serial_xmit(GIOChannel *chan, GIOCondition cond, void *opaque)
{
SerialState *s = opaque;
- uint64_t new_xmit_ts = qemu_get_clock_ns(vm_clock);
if (s->tsr_retry <= 0) {
if (s->fcr & UART_FCR_FE) {
s->tsr = fifo_get(s,XMIT_FIFO);
if (!s->xmit_fifo.count)
s->lsr |= UART_LSR_THRE;
+ } else if ((s->lsr & UART_LSR_THRE)) {
+ return FALSE;
} else {
s->tsr = s->thr;
s->lsr |= UART_LSR_THRE;
@@ -277,30 +278,25 @@ static void serial_xmit(void *opaque)
/* in loopback mode, say that we just received a char */
serial_receive1(s, &s->tsr, 1);
} else if (qemu_chr_fe_write(s->chr, &s->tsr, 1) != 1) {
- if ((s->tsr_retry > 0) && (s->tsr_retry <= MAX_XMIT_RETRY)) {
+ if (s->tsr_retry >= 0 && s->tsr_retry < MAX_XMIT_RETRY &&
+ qemu_chr_fe_add_watch(s->chr, G_IO_OUT, serial_xmit, s) > 0) {
s->tsr_retry++;
- qemu_mod_timer(s->transmit_timer, new_xmit_ts + s->char_transmit_time);
- return;
- } else if (s->poll_msl < 0) {
- /* If we exceed MAX_XMIT_RETRY and the backend is not a real serial port, then
- drop any further failed writes instantly, until we get one that goes through.
- This is to prevent guests that log to unconnected pipes or pty's from stalling. */
- s->tsr_retry = -1;
+ return FALSE;
}
- }
- else {
+ s->tsr_retry = 0;
+ } else {
s->tsr_retry = 0;
}
s->last_xmit_ts = qemu_get_clock_ns(vm_clock);
- if (!(s->lsr & UART_LSR_THRE))
- qemu_mod_timer(s->transmit_timer, s->last_xmit_ts + s->char_transmit_time);
if (s->lsr & UART_LSR_THRE) {
s->lsr |= UART_LSR_TEMT;
s->thr_ipending = 1;
serial_update_irq(s);
}
+
+ return FALSE;
}
@@ -330,7 +326,7 @@ static void serial_ioport_write(void *opaque, hwaddr addr, uint64_t val,
s->lsr &= ~UART_LSR_THRE;
serial_update_irq(s);
}
- serial_xmit(s);
+ serial_xmit(NULL, G_IO_OUT, s);
}
break;
case 1:
@@ -684,8 +680,6 @@ void serial_init_core(SerialState *s)
s->modem_status_poll = qemu_new_timer_ns(vm_clock, (QEMUTimerCB *) serial_update_msl, s);
s->fifo_timeout_timer = qemu_new_timer_ns(vm_clock, (QEMUTimerCB *) fifo_timeout_int, s);
- s->transmit_timer = qemu_new_timer_ns(vm_clock, (QEMUTimerCB *) serial_xmit, s);
-
qemu_register_reset(serial_reset, s);
qemu_chr_add_handlers(s->chr, serial_can_receive1, serial_receive1,