[RFC i-g-t v3 2/5] igt_aux: Add igt_set_autoresume_delay()

[Lyude <lyude@redhat.com>]

The default autoresume delay is about 5 seconds. It's possible on a
system that's not very fast this might not be a long enough time, since
an asynchronous hotplug event we scheduled on the chamelium that was
intended to happen during suspend could happen before we actually manage
to suspend. So, add a function that allows us to increase the autoresume
time to ensure this never happens during suspend/resume tests with the
chamelium.

Signed-off-by: Lyude <lyude@redhat.com>

Changes since v1:
- Use igt_require, not assert
---
 lib/igt_aux.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_aux.h |  1 +
 2 files changed, 47 insertions(+)

diff --git a/lib/igt_aux.c b/lib/igt_aux.c
index ce2f245..babec57 100644
--- a/lib/igt_aux.c
+++ b/lib/igt_aux.c
@@ -801,6 +801,52 @@ void igt_system_suspend_autoresume(enum igt_suspend_state state,
 	close(power_dir);
 }
 
+static int original_autoresume_delay;
+
+static void igt_restore_autoresume_delay(int sig)
+{
+	int delay_fd;
+	char delay_str[10];
+
+	igt_require((delay_fd = open("/sys/module/suspend/parameters/pm_test_delay",
+				    O_WRONLY)) >= 0);
+
+	snprintf(delay_str, sizeof(delay_str), "%d", original_autoresume_delay);
+	igt_require(write(delay_fd, delay_str, strlen(delay_str)));
+
+	close(delay_fd);
+}
+
+/**
+ * igt_set_autoresume_delay:
+ * @delay_secs: The delay in seconds before resuming the system
+ *
+ * Sets how long we wait to resume the system after suspending it, using the
+ * suspend.pm_test_delay variable. On exit, the original delay value is
+ * restored.
+ */
+void igt_set_autoresume_delay(int delay_secs)
+{
+	int delay_fd;
+	char delay_str[10];
+
+	igt_skip_on_simulation();
+
+	igt_require((delay_fd = open("/sys/module/suspend/parameters/pm_test_delay",
+				    O_RDWR)) >= 0);
+
+	if (!original_autoresume_delay) {
+		igt_require(read(delay_fd, delay_str, sizeof(delay_str)));
+		original_autoresume_delay = atoi(delay_str);
+		igt_install_exit_handler(igt_restore_autoresume_delay);
+	}
+
+	snprintf(delay_str, sizeof(delay_str), "%d", delay_secs);
+	igt_require(write(delay_fd, delay_str, strlen(delay_str)));
+
+	close(delay_fd);
+}
+
 /**
  * igt_drop_root:
  *
diff --git a/lib/igt_aux.h b/lib/igt_aux.h
index 41903c2..2c58abc 100644
--- a/lib/igt_aux.h
+++ b/lib/igt_aux.h
@@ -185,6 +185,7 @@ void igt_skip_without_suspend_support(enum igt_suspend_state state,
 				      enum igt_suspend_test test);
 void igt_system_suspend_autoresume(enum igt_suspend_state state,
 				   enum igt_suspend_test test);
+void igt_set_autoresume_delay(int delay_secs);
 
 /* dropping priviledges */
 void igt_drop_root(void);
-- 
2.9.3

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