* [Qemu-devel] [PATCH] Fix lost serial TX interrupts. Report receive overruns.
@ 2010-01-28 23:13 Justin T. Gibbs
2010-02-10 17:58 ` Anthony Liguori
2010-02-10 22:37 ` [Qemu-devel] " Justin T. Gibbs
0 siblings, 2 replies; 4+ messages in thread
From: Justin T. Gibbs @ 2010-01-28 23:13 UTC (permalink / raw)
To: qemu-devel
This patch compliments the patch submitted by Jergen Lock and further
improves the performance of QEMU's serial emulation with FreeBSD's
uart(9) driver.
o Implement receive overrun status. The FreeBSD uart driver
relies on this status in it's probe routine to determine the size
of the FIFO supported.
o As per the 16550 spec, do not overwrite the RX FIFO on an RX overrun.
o Do not allow TX or RX FIFO overruns to increment the data valid count
beyond the size of the FIFO.
o For reads of the IIR register, only clear the "TX holding register
emtpy interrupt" if the read reports this interrupt. This is required
by the specification and avoids losing TX interrupts when other, higher
priority interrupts (usually RX) are reported first.
Signed-off-by: Justin T. Gibbs <gibbs@FreeBSD.org>
--- serial.c.orig Thu Jan 14 15:18:00 2010
+++ serial.c Thu Jan 28 15:36:04 2010
@@ -169,11 +169,19 @@
{
SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
- f->data[f->head++] = chr;
+ /* Receive overruns do not overwrite FIFO contents. */
+ if (fifo == XMIT_FIFO || f->count < UART_FIFO_LENGTH) {
- if (f->head == UART_FIFO_LENGTH)
- f->head = 0;
- f->count++;
+ f->data[f->head++] = chr;
+
+ if (f->head == UART_FIFO_LENGTH)
+ f->head = 0;
+ }
+
+ if (f->count < UART_FIFO_LENGTH)
+ f->count++;
+ else if (fifo == RECV_FIFO)
+ s->lsr |= UART_LSR_OE;
return 1;
}
@@ -533,8 +541,10 @@
break;
case 2:
ret = s->iir;
+ if (ret & UART_IIR_THRI) {
s->thr_ipending = 0;
- serial_update_irq(s);
+ serial_update_irq(s);
+ }
break;
case 3:
ret = s->lcr;
@@ -544,9 +554,9 @@
break;
case 5:
ret = s->lsr;
- /* Clear break interrupt */
- if (s->lsr & UART_LSR_BI) {
- s->lsr &= ~UART_LSR_BI;
+ /* Clear break and overrun interrupts */
+ if (s->lsr & (UART_LSR_BI|UART_LSR_OE)) {
+ s->lsr &= ~(UART_LSR_BI|UART_LSR_OE);
serial_update_irq(s);
}
break;
@@ -629,6 +639,8 @@
/* call the timeout receive callback in 4 char transmit time */
qemu_mod_timer(s->fifo_timeout_timer, qemu_get_clock
(vm_clock) + s->char_transmit_time * 4);
} else {
+ if (s->lsr & UART_LSR_DR)
+ s->lsr |= UART_LSR_OE;
s->rbr = buf[0];
s->lsr |= UART_LSR_DR;
}
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH] Fix lost serial TX interrupts. Report receive overruns.
2010-01-28 23:13 [Qemu-devel] [PATCH] Fix lost serial TX interrupts. Report receive overruns Justin T. Gibbs
@ 2010-02-10 17:58 ` Anthony Liguori
2010-02-10 22:37 ` [Qemu-devel] " Justin T. Gibbs
1 sibling, 0 replies; 4+ messages in thread
From: Anthony Liguori @ 2010-02-10 17:58 UTC (permalink / raw)
To: gibbs; +Cc: qemu-devel
On 01/28/2010 05:13 PM, Justin T. Gibbs wrote:
> This patch compliments the patch submitted by Jergen Lock and further
> improves the performance of QEMU's serial emulation with FreeBSD's
> uart(9) driver.
>
> o Implement receive overrun status. The FreeBSD uart driver
> relies on this status in it's probe routine to determine the size
> of the FIFO supported.
> o As per the 16550 spec, do not overwrite the RX FIFO on an RX overrun.
> o Do not allow TX or RX FIFO overruns to increment the data valid count
> beyond the size of the FIFO.
> o For reads of the IIR register, only clear the "TX holding register
> emtpy interrupt" if the read reports this interrupt. This is required
> by the specification and avoids losing TX interrupts when other,
> higher
> priority interrupts (usually RX) are reported first.
>
> Signed-off-by: Justin T. Gibbs <gibbs@FreeBSD.org>
This patch is malformed. Please export the patch from a git tree via
git-format-patch.
Regards,
Anthony Liguori
>
> --- serial.c.orig Thu Jan 14 15:18:00 2010
> +++ serial.c Thu Jan 28 15:36:04 2010
> @@ -169,11 +169,19 @@
> {
> SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
>
> - f->data[f->head++] = chr;
> + /* Receive overruns do not overwrite FIFO contents. */
> + if (fifo == XMIT_FIFO || f->count < UART_FIFO_LENGTH) {
>
> - if (f->head == UART_FIFO_LENGTH)
> - f->head = 0;
> - f->count++;
> + f->data[f->head++] = chr;
> +
> + if (f->head == UART_FIFO_LENGTH)
> + f->head = 0;
> + }
> +
> + if (f->count < UART_FIFO_LENGTH)
> + f->count++;
> + else if (fifo == RECV_FIFO)
> + s->lsr |= UART_LSR_OE;
>
> return 1;
> }
> @@ -533,8 +541,10 @@
> break;
> case 2:
> ret = s->iir;
> + if (ret & UART_IIR_THRI) {
> s->thr_ipending = 0;
> - serial_update_irq(s);
> + serial_update_irq(s);
> + }
> break;
> case 3:
> ret = s->lcr;
> @@ -544,9 +554,9 @@
> break;
> case 5:
> ret = s->lsr;
> - /* Clear break interrupt */
> - if (s->lsr & UART_LSR_BI) {
> - s->lsr &= ~UART_LSR_BI;
> + /* Clear break and overrun interrupts */
> + if (s->lsr & (UART_LSR_BI|UART_LSR_OE)) {
> + s->lsr &= ~(UART_LSR_BI|UART_LSR_OE);
> serial_update_irq(s);
> }
> break;
> @@ -629,6 +639,8 @@
> /* call the timeout receive callback in 4 char transmit time */
> qemu_mod_timer(s->fifo_timeout_timer, qemu_get_clock
> (vm_clock) + s->char_transmit_time * 4);
> } else {
> + if (s->lsr & UART_LSR_DR)
> + s->lsr |= UART_LSR_OE;
> s->rbr = buf[0];
> s->lsr |= UART_LSR_DR;
> }
>
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* [Qemu-devel] Re: [PATCH] Fix lost serial TX interrupts. Report receive overruns.
2010-01-28 23:13 [Qemu-devel] [PATCH] Fix lost serial TX interrupts. Report receive overruns Justin T. Gibbs
2010-02-10 17:58 ` Anthony Liguori
@ 2010-02-10 22:37 ` Justin T. Gibbs
2010-02-22 22:20 ` Anthony Liguori
1 sibling, 1 reply; 4+ messages in thread
From: Justin T. Gibbs @ 2010-02-10 22:37 UTC (permalink / raw)
To: qemu-devel
[-- Attachment #1: Type: text/plain, Size: 50 bytes --]
Properly formatted patch now attached.
--
Justin
[-- Attachment #2: 0001-Fix-lost-serial-TX-interrupts.-Report-receive-overruns.patch --]
[-- Type: text/plain, Size: 2961 bytes --]
>From 7a941b3fcd298b60bb14744b8fae422d86298197 Mon Sep 17 00:00:00 2001
From: Justin T. Gibbs <gibbs@FreeBSD.org>
Date: Wed, 10 Feb 2010 14:35:54 -0700
Subject: [PATCH] Fix lost serial TX interrupts. Report receive overruns.
o Implement receive overrun status. The FreeBSD uart driver
relies on this status in it's probe routine to determine the size
of the FIFO supported.
o As per the 16550 spec, do not overwrite the RX FIFO on an RX overrun.
o Do not allow TX or RX FIFO overruns to increment the data valid count
beyond the size of the FIFO.
o For reads of the IIR register, only clear the "TX holding register
emtpy interrupt" if the read reports this interrupt. This is required
by the specification and avoids losing TX interrupts when other,
higher priority interrupts (usually RX) are reported first.
Signed-off-by: Justin T. Gibbs <gibbs@FreeBSD.org>
---
hw/serial.c | 28 ++++++++++++++++++++--------
1 files changed, 20 insertions(+), 8 deletions(-)
diff --git a/hw/serial.c b/hw/serial.c
index e7538ac..df67383 100644
--- a/hw/serial.c
+++ b/hw/serial.c
@@ -169,11 +169,19 @@ static int fifo_put(SerialState *s, int fifo, uint8_t chr)
{
SerialFIFO *f = (fifo) ? &s->recv_fifo : &s->xmit_fifo;
- f->data[f->head++] = chr;
+ /* Receive overruns do not overwrite FIFO contents. */
+ if (fifo == XMIT_FIFO || f->count < UART_FIFO_LENGTH) {
- if (f->head == UART_FIFO_LENGTH)
- f->head = 0;
- f->count++;
+ f->data[f->head++] = chr;
+
+ if (f->head == UART_FIFO_LENGTH)
+ f->head = 0;
+ }
+
+ if (f->count < UART_FIFO_LENGTH)
+ f->count++;
+ else if (fifo == RECV_FIFO)
+ s->lsr |= UART_LSR_OE;
return 1;
}
@@ -533,8 +541,10 @@ static uint32_t serial_ioport_read(void *opaque, uint32_t addr)
break;
case 2:
ret = s->iir;
+ if (ret & UART_IIR_THRI) {
s->thr_ipending = 0;
- serial_update_irq(s);
+ serial_update_irq(s);
+ }
break;
case 3:
ret = s->lcr;
@@ -544,9 +554,9 @@ static uint32_t serial_ioport_read(void *opaque, uint32_t addr)
break;
case 5:
ret = s->lsr;
- /* Clear break interrupt */
- if (s->lsr & UART_LSR_BI) {
- s->lsr &= ~UART_LSR_BI;
+ /* Clear break and overrun interrupts */
+ if (s->lsr & (UART_LSR_BI|UART_LSR_OE)) {
+ s->lsr &= ~(UART_LSR_BI|UART_LSR_OE);
serial_update_irq(s);
}
break;
@@ -629,6 +639,8 @@ static void serial_receive1(void *opaque, const uint8_t *buf, int size)
/* call the timeout receive callback in 4 char transmit time */
qemu_mod_timer(s->fifo_timeout_timer, qemu_get_clock (vm_clock) + s->char_transmit_time * 4);
} else {
+ if (s->lsr & UART_LSR_DR)
+ s->lsr |= UART_LSR_OE;
s->rbr = buf[0];
s->lsr |= UART_LSR_DR;
}
--
1.6.6
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2010-01-28 23:13 [Qemu-devel] [PATCH] Fix lost serial TX interrupts. Report receive overruns Justin T. Gibbs
2010-02-10 17:58 ` Anthony Liguori
2010-02-10 22:37 ` [Qemu-devel] " Justin T. Gibbs
2010-02-22 22:20 ` Anthony Liguori
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