tests: pwm_loopback: Capture disable omission issue

As per the PWM API definition, -EBUSY should be returned
when pwm_enable_capture is called and capturing
is already enabled. This commit deals with adding
a ztest_suite_before_t function that should disable
capturing at the end of a single test. Some tests, though,
such as test_pulse_capture, execute two sub-tests
and so, capturing is disabled in between. In fact, the omission
of pwm_disable_capture should not only result in aborting
a single test, but it can also raise system exception
due to invalid context. This is the case for
z_impl_pwm_capture_cycles where z_pwm_capture_cycles_callback
can be fired whilst the routine has already aborted and so
struct z_pwm_capture_cb_data data, defined within function
declaration, should not longer be valid.

Signed-off-by: Ioannis Karachalios <[email protected]>

Author: ioannis-karachalios

tests/drivers/pwm/pwm_loopback/src/main.c

@@ -22,4 +22,18 @@ static void *pwm_loopback_setup(void)
 	return NULL;
 }
 
-ZTEST_SUITE(pwm_loopback, NULL, pwm_loopback_setup, NULL, NULL, NULL);
+static void pwm_loopback_after(void *f)
+{
+	struct test_pwm in;
+	struct test_pwm out;
+	int err;
+
+	ARG_UNUSED(f);
+
+	get_test_pwms(&out, &in);
+
+	err = pwm_disable_capture(in.dev, in.pwm);
+	zassert_equal(err, 0, "failed to disable pwm capture (err %d)", err);
+}
+
+ZTEST_SUITE(pwm_loopback, NULL, pwm_loopback_setup, NULL, pwm_loopback_after, NULL);

tests/drivers/pwm/pwm_loopback/src/test_pwm_loopback.c

@@ -85,6 +85,8 @@ static void test_capture(uint32_t period, uint32_t pulse, enum test_pwm_unit uni
 		ztest_test_fail();
 	}
 
+	pwm_disable_capture(in.dev, in.pwm);
+
 	if (err == -ENOTSUP) {
 		TC_PRINT("capture type not supported\n");
 		ztest_test_skip();