[igt-dev] [PATCH i-g-t 3/3] tests/kms_chamelium: Introduce HPD short storm tests

[Lyude <lyude@redhat.com>]

From: Lyude Paul <lyude@redhat.com>

This is to follow up with the changes that were recently made to HPD
storm detection in https://patchwork.freedesktop.org/patch/260597/ , as
now there are systems which will be counting short IRQs towards HPD
storms. As such, we introduce helpers to control HPD short storm
detection, along with some new kms_chamelium tests for it.

Please note that at the time of writing this: these tests currently
fail. That is because the i915_hpd_storm_ctl debugfs currently forgets
to synchronize with all IRQs and hotplugging work before returning the
HPD storm status to the user. A patch for this will be sent onto the ML
very shortly.

Signed-off-by: Lyude Paul <lyude@redhat.com>
---
 lib/igt_debugfs.c     | 85 +++++++++++++++++++++++++++++++++++++++++++
 lib/igt_debugfs.h     |  4 ++
 tests/kms_chamelium.c | 45 +++++++++++++++++++++++
 3 files changed, 134 insertions(+)

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index 358b4cab..530b70b7 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -543,6 +543,7 @@ static void igt_hpd_storm_exit_handler(int sig)
 	int fd = drm_open_driver(DRIVER_INTEL);
 
 	/* Here we assume that only one i915 device will be ever present */
+	igt_hpd_short_storm_reset(fd);
 	igt_hpd_storm_reset(fd);
 
 	close(fd);
@@ -660,6 +661,90 @@ void igt_require_hpd_storm_ctl(int drm_fd)
 
 	igt_require_f(fd > 0, "No i915_hpd_storm_ctl found in debugfs\n");
 	close(fd);
+
+	fd = igt_debugfs_open(drm_fd, "i915_hpd_short_storm_ctl", O_RDONLY);
+	igt_require_f(fd > 0, "No i915_hpd_short_storm_ctl found in debugfs\n");
+	close(fd);
+}
+
+/**
+ * igt_hpd_short_storm_set_enabled:
+ *
+ * Convienence helper to enable or disable HPD short storm detection. If hotplug
+ * detection was disabled on any ports due to an HPD storm, it will be
+ * immediately re-enabled.
+ *
+ * If the system does not support HPD storm detection, this function does
+ * nothing.
+ *
+ * See: https://01.org/linuxgraphics/gfx-docs/drm/gpu/i915.html#hotplug
+ */
+void igt_hpd_short_storm_set_enabled(int drm_fd, bool enabled)
+{
+	int fd = igt_debugfs_open(drm_fd, "i915_hpd_short_storm_ctl", O_WRONLY);
+	const char *buf = enabled ? "y" : "n";
+
+	if (fd < 0)
+		return;
+
+	igt_debug("%sabling HPD short storm detection\n",
+		  enabled ? "En" : "Dis");
+	igt_assert_eq(write(fd, buf, strlen(buf)), strlen(buf));
+
+	close(fd);
+}
+
+/**
+ * igt_hpd_short_storm_reset:
+ *
+ * Convienence helper to reset HPD short storm detection to it's default settings.
+ * If hotplug detection was disabled on any ports due to an HPD storm, it will
+ * be immediately re-enabled. Always called on exit if the HPD storm detection
+ * threshold was modified during any tests.
+ *
+ * If the system does not support HPD storm detection, this function does
+ * nothing.
+ *
+ * See: https://01.org/linuxgraphics/gfx-docs/drm/gpu/i915.html#hotplug
+ */
+void igt_hpd_short_storm_reset(int drm_fd)
+{
+	int fd = igt_debugfs_open(drm_fd, "i915_hpd_short_storm_ctl", O_WRONLY);
+	const char *buf = "reset";
+
+	if (fd < 0)
+		return;
+
+	igt_debug("Resetting HPD short storm detection\n");
+	igt_assert_eq(write(fd, buf, strlen(buf)), strlen(buf));
+
+	close(fd);
+}
+
+/**
+ * igt_require_hpd_short_storm_on_by_default:
+ *
+ * Skips the current test if the system does not have HPD short storm detection
+ * enabled by default.
+ *
+ * See: https://01.org/linuxgraphics/gfx-docs/drm/gpu/i915.html#hotplug
+ */
+void igt_require_hpd_short_storm_on_by_default(int drm_fd)
+{
+	int fd;
+	char buf[16] = {0};
+
+	/* First reset short storm detection to the system default */
+	igt_hpd_short_storm_reset(drm_fd);
+
+	/* Now check if the default is enabled or not */
+	fd = igt_debugfs_open(drm_fd, "i915_hpd_short_storm_ctl", O_RDONLY);
+
+	igt_require_f(fd > 0, "No i915_hpd_short_storm_ctl found in debugfs\n");
+	igt_assert_lt(0, read(fd, buf, sizeof(buf)));
+	igt_require_f(strncmp(buf, "Enabled: yes\n", sizeof(buf)) == 0,
+		      "System keeps HPD short storm detection disabled by default\n");
+	close(fd);
 }
 
 static igt_pipe_crc_t *
diff --git a/lib/igt_debugfs.h b/lib/igt_debugfs.h
index 1233cd8f..21b382a3 100644
--- a/lib/igt_debugfs.h
+++ b/lib/igt_debugfs.h
@@ -143,6 +143,10 @@ void igt_hpd_storm_reset(int fd);
 bool igt_hpd_storm_detected(int fd);
 void igt_require_hpd_storm_ctl(int fd);
 
+void igt_hpd_short_storm_set_enabled(int fd, bool enabled);
+void igt_hpd_short_storm_reset(int fd);
+void igt_require_hpd_short_storm_on_by_default(int fd);
+
 /*
  * Drop caches
  */
diff --git a/tests/kms_chamelium.c b/tests/kms_chamelium.c
index 0097dbcc..7ab33830 100644
--- a/tests/kms_chamelium.c
+++ b/tests/kms_chamelium.c
@@ -45,6 +45,7 @@ typedef struct {
 #define HOTPLUG_TIMEOUT 20 /* seconds */
 
 #define HPD_STORM_PULSE_INTERVAL_DP 100 /* ms */
+#define HPD_SHORT_STORM_PULSE_INTERVAL_DP 2 /* ms */
 #define HPD_STORM_PULSE_INTERVAL_HDMI 200 /* ms */
 
 #define HPD_TOGGLE_COUNT_VGA 5
@@ -775,6 +776,44 @@ test_hpd_storm_disable(data_t *data, struct chamelium_port *port, int width)
 	igt_hpd_storm_reset(data->drm_fd);
 }
 
+static void
+test_hpd_short_storm_detect(data_t *data, struct chamelium_port *port)
+{
+	igt_require_hpd_storm_ctl(data->drm_fd);
+	igt_require_hpd_short_storm_on_by_default(data->drm_fd);
+	reset_state(data, port);
+
+	/* Leave room in the threshold for the two long pulses this might
+	 * cause
+	 */
+	igt_hpd_storm_set_threshold(data->drm_fd, 21);
+	chamelium_fire_hpd_pulses(data->chamelium, port,
+				  HPD_SHORT_STORM_PULSE_INTERVAL_DP, 25, false);
+	igt_assert(igt_hpd_storm_detected(data->drm_fd));
+
+	igt_hpd_storm_reset(data->drm_fd);
+}
+
+static void
+test_hpd_short_storm_disable(data_t *data, struct chamelium_port *port)
+{
+	igt_require_hpd_storm_ctl(data->drm_fd);
+	reset_state(data, port);
+
+	igt_hpd_short_storm_set_enabled(data->drm_fd, false);
+
+	/* Leave room in the threshold for the two long pulses this might
+	 * cause
+	 */
+	igt_hpd_storm_set_threshold(data->drm_fd, 21);
+	chamelium_fire_hpd_pulses(data->chamelium, port,
+				  HPD_SHORT_STORM_PULSE_INTERVAL_DP, 25, false);
+	igt_assert(!igt_hpd_storm_detected(data->drm_fd));
+
+	igt_hpd_short_storm_reset(data->drm_fd);
+	igt_hpd_storm_reset(data->drm_fd);
+}
+
 #define for_each_port(p, port)            \
 	for (p = 0, port = data.ports[p]; \
 	     p < data.port_count;         \
@@ -856,6 +895,12 @@ igt_main
 			test_hpd_storm_disable(&data, port,
 					       HPD_STORM_PULSE_INTERVAL_DP);
 
+		connector_subtest("dp-hpd-short-storm", DisplayPort)
+			test_hpd_short_storm_detect(&data, port);
+
+		connector_subtest("dp-hpd-short-storm-disable", DisplayPort)
+			test_hpd_short_storm_disable(&data, port);
+
 		connector_subtest("dp-edid-change-during-suspend", DisplayPort)
 			test_suspend_resume_edid_change(&data, port,
 							SUSPEND_STATE_MEM,
-- 
2.19.1

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