Hi Thomas and Phil,
On 11/13/23 7:14 AM, Philippe Mathieu-Daudé wrote:
On 13/11/23 07:59, Thomas Huth wrote:
On 12/11/2023 02.38, Gustavo Romero wrote:
Currently the QTest API does not provide a function to allow capturing
when an IRQ line is toggled (raised then lowered). Functions like
qtest_get_irq() read the current state of the intercepted IRQ lines,
which is already low when the function is called, since the line is
toggled.
This commit introduces a new function, qtest_get_irq_trigger_counter(),
which returns the number of times a given intercepted IRQ line was
triggered (raised), hence allowing to capture when an IRQ line was
toggled.
Signed-off-by: Gustavo Romero <gustavo.rom...@linaro.org>
---
tests/qtest/libqtest.c | 12 ++++++++++++
tests/qtest/libqtest.h | 9 +++++++++
2 files changed, 21 insertions(+)
diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
index f33a210861..21891b52f1 100644
--- a/tests/qtest/libqtest.c
+++ b/tests/qtest/libqtest.c
@@ -82,6 +82,7 @@ struct QTestState
int expected_status;
bool big_endian;
bool irq_level[MAX_IRQ];
+ uint64_t irq_trigger_counter[MAX_IRQ];
GString *rx;
QTestTransportOps ops;
GList *pending_events;
@@ -498,6 +499,7 @@ static QTestState *qtest_init_internal(const char *qemu_bin,
s->rx = g_string_new("");
for (i = 0; i < MAX_IRQ; i++) {
s->irq_level[i] = false;
+ s->irq_trigger_counter[i] = 0;
}
/*
@@ -690,6 +692,7 @@ redo:
if (strcmp(words[1], "raise") == 0) {
s->irq_level[irq] = true;
+ s->irq_trigger_counter[irq]++;
This is 'irq_raised_counter',
Not sure whether you can get some "raise" events in a row without some "lower"
events in between ... but just in case, I wonder whether it would make sense to check whether it is
really a rising edge, i.e.:
if (strcmp(words[1], "raise") == 0) {
if (!s->irq_level[irq]) {
s->irq_trigger_counter[irq]++;
}
s->irq_level[irq] = true;
What do you think?
This is 'irq_pulsed_counter'. 'irq_lowered_counter' could also be
useful (at least for completeness).
I understand that the code provided by Thomas actually has the exactly same
effect as my code. This happens because a "raise" (or "low) message is
not sent by the "server" side unless a transition state low -> high happens,
so the check 'if (!s->irq_level[irq]) { ... }' is always true. So it's still
capturing the raising state transition (as a side note, when one intercepts
an IRQ the current state of the IRQ line is saved -- so the old IRQ state is
always valid). Therefore, also as a consequence, like Thomas said, it's not
possible to get a 'raise' event in a row without a 'lower' event in between.
Based on your comments, I gave a second thought on 'trigger' meaning. I think
'trigger' refers to an event or action that automatically initiates a
procedure. Since raising an IRQ line does not always mean to generate an IRQ,
since the like can be active low in a device, maybe I should avoid using
trigger and synonymous for raising.
I think since 'toggle' means to switch back and forth between two modes or
states, yep, it seems ok to me to use it as a synonymous for 'pulse'.
Hence, I removed the word 'trigger' from the API function name and elsewhere.
Right, I think having a qtest_get_irq_lowered_counter() is better and also,
when used together with qtest_get_irq_raised_counter(), it's possible for a
test to check pulses on the IRQ lines.
Per Gustavo's description, he indeed wants irq_pulsed_counter (or
irq_toggled_counter'.
That's a good point. So far I was testing just the high -> low transition,
but in fact the most correct way to test the device is also check for
a high -> low transition (so, yeah, indeed test a pulse).
In the device I have:
[...]
/*
* Toggle device's output line, which is connected to interrupt controller,
* generating an interrupt request to the CPU.
*/
qemu_set_irq(s->irq, true);
qemu_set_irq(s->irq, false);
}
Thus having both qtest_get_irq_{lowered,raised}_counter() allows capturing
an IRQ toggle, for instance, as the following, where exactly 1 pulse is tested:
uint64_t num_raises;
uint64_t num_lows;
while (1) {
if ((num_raises = qtest_get_irq_raised_counter(qts, 0))) {
num_lows = qtest_get_irq_lowered_counter(qts, 0);
if (num_raises == num_lows && num_lows == 1) {
printf("Detected correct number of pulses.\n");
return 0;
} else {
printf("Detected incorrect number of pulses.\n");
return 1;
}
}
}
} else {
s->irq_level[irq] = false;
}
Anyway:
Acked-by: Thomas Huth <th...@redhat.com>
I'm sending a v2 with qtest_get_irq_lowered_counter().
Thanks!
Cheers,
Gustavo
