[Intel-gfx] [PATCH i-g-t] tests/pm_backlight: Enable connected output to allow tests to succeed, v2.

[Maarten Lankhorst]

If the connected output is disabled before this test is run, then the test
will fail because actual_brightness stays at 0 instead of the value
of the desired brightness. Fix this by reading intel_backlight/device
for the output name, and enable that output at start of this test.

Changes since v1:
- Enable the connected output, instead of enabling all outputs.

Sample failure:
IGT-Version: 1.20-g01c550a27986 (x86_64) (Linux: 4.14.0-rc3-fbconhax+ x86_64)
(pm_backlight:1203) CRITICAL: Test assertion failure function test_and_verify, file pm_backlight.c:111:
(pm_backlight:1203) CRITICAL: Failed assertion: ({ typeof(0) _a = (0); typeof(val - tolerance) _b = (val - tolerance); _a > _b ? _a : _b; }) <= result
(pm_backlight:1203) CRITICAL: error: 91200 > 0

Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
---
 tests/pm_backlight.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/tests/pm_backlight.c b/tests/pm_backlight.c
index 8258d4e4c124..6909f7dc64b3 100644
--- a/tests/pm_backlight.c
+++ b/tests/pm_backlight.c
@@ -155,13 +155,44 @@ igt_main
 {
 	struct context context = {0};
 	int old;
+	igt_display_t display;
 
 	igt_skip_on_simulation();
 
 	igt_fixture {
+		enum pipe pipe;
+		igt_output_t *output;
+		bool found = false;
+		char full_name[32] = {};
+		char *name;
+
 		/* Get the max value and skip the whole test if sysfs interface not available */
 		igt_skip_on(backlight_read(&old, "brightness"));
 		igt_assert(backlight_read(&context.max, "max_brightness") > -1);
+
+		/*
+		 * Backlight tests requires the output to be enabled,
+		 * try to enable all.
+		 */
+		kmstest_set_vt_graphics_mode();
+		igt_display_init(&display, drm_open_driver(DRIVER_INTEL));
+
+		/* should be ../../cardX-$output */
+		igt_assert_lt(12, readlink(BACKLIGHT_PATH "/device", full_name, sizeof(full_name) - 1));
+		name = basename(full_name);
+
+		for_each_pipe_with_valid_output(&display, pipe, output) {
+			if (strcmp(name + 6, output->name))
+				continue;
+
+			igt_output_set_pipe(output, pipe);
+			found = true;
+			break;
+		}
+
+		igt_assert_f(found, "Could not map \"%s\" to output (%s?)\n", name, name + 6);
+
+		igt_display_commit2(&display, display.is_atomic ? COMMIT_ATOMIC : COMMIT_LEGACY);
 	}
 
 	igt_subtest("basic-brightness")
@@ -174,5 +205,8 @@ igt_main
 	igt_fixture {
 		/* Restore old brightness */
 		backlight_write(old, "brightness");
+
+		igt_display_fini(&display);
+		close(display.drm_fd);
 	}
 }
-- 
2.14.1