[PATCH v2 1/1] tests/kms_vrr: Skip LOBF test when aux-less ALPM is not enabled

[Mohammed Bilal <mohammed.bilal@intel.com>]

LOBF (Link Off Between Frames) is a feature introduced in eDP 1.5+
that can operate in both Aux-less ALPM (Advanced Link Power Management) 
and AUX-Wake ALPM modes.Currently, the test relies on Aux-less 
ALPM support to validate LOBF functionality.

Add a helper to read the Aux-less ALPM status from debugfs and
skip the LOBF subtest when Aux-less ALPM is not enabled on the
panel, avoiding false failures on systems that may only support
AUX-Wake ALPM or lack ALPM support entirely.

-v2:

-Update commit message (Jeevan)
-Update commit message for LOBF/ALPM clarification (Kamil)
-Rename function to igt_is_aux_less_alpm_enabled (Sebastien)
-Add explicit null-termination (Sebastien)
-Add igt_info() log (Sowmiya)

Signed-off-by: Mohammed Bilal <mohammed.bilal@intel.com>
---
 lib/igt_kms.c   | 32 ++++++++++++++++++++++++++++++++
 lib/igt_kms.h   |  1 +
 tests/kms_vrr.c |  6 ++++++
 3 files changed, 39 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 5c4879604..5f7def664 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -6578,6 +6578,38 @@ bool igt_get_i915_edp_lobf_status(int drmfd, char *connector_name)
 	return strstr(buf, "LOBF status: enabled");
 }
 
+/**
+ * igt_is_aux_less_alpm_enabled
+ * @drmfd: A drm file descriptor
+ * @connector_name: Name of the libdrm connector we're going to use
+ *
+ * Check if Aux-less ALPM (Advanced Link Power Management) mode is enabled by reading
+ * the i915_edp_lobf_info debugfs.
+ *
+ * Return: True if aux-less ALPM is enabled.
+ */
+bool igt_is_aux_less_alpm_enabled(int drmfd, char *connector_name)
+{
+	char buf[256];
+	int fd, res;
+
+	fd = igt_debugfs_connector_dir(drmfd, connector_name, O_RDONLY);
+	if (fd < 0)
+		return false;
+
+	res = igt_debugfs_simple_read(fd, "i915_edp_lobf_info", buf, sizeof(buf));
+	close(fd);
+
+	if (res <= 0) {
+		igt_info("Failed to read i915_edp_lobf_info for %s\n", connector_name);
+		return false;
+	}
+
+	buf[res < sizeof(buf) ? res : sizeof(buf) - 1] = '\0';
+
+	return strstr(buf, "Aux-less alpm status: enabled") != NULL;
+}
+
 /**
  * igt_get_output_max_bpc:
  * @drmfd: A drm file descriptor
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index dedc3f880..c2fc53953 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1257,6 +1257,7 @@ bool igt_override_all_active_output_modes_to_fit_bw(igt_display_t *display);
 bool igt_fit_modes_in_bw(igt_display_t *display);
 bool igt_has_lobf_debugfs(int drmfd, igt_output_t *output);
 bool igt_get_i915_edp_lobf_status(int drmfd, char *connector_name);
+bool igt_is_aux_less_alpm_enabled(int drmfd, char *connector_name);
 unsigned int igt_get_output_max_bpc(int drmfd, char *connector_name);
 unsigned int igt_get_pipe_current_bpc(int drmfd, enum pipe pipe);
 void igt_assert_output_bpc_equal(int drmfd, enum pipe pipe,
diff --git a/tests/kms_vrr.c b/tests/kms_vrr.c
index 811596ec2..c1f69ac54 100644
--- a/tests/kms_vrr.c
+++ b/tests/kms_vrr.c
@@ -1013,6 +1013,12 @@ static bool output_constraint(data_t *data, igt_output_t *output, uint32_t flags
 			return false;
 		}
 
+		if (!igt_is_aux_less_alpm_enabled(data->drm_fd, output->name)) {
+			igt_info("%s: Aux-less ALPM not enabled, LOBF not supported.\n",
+				 igt_output_name(output));
+			return false;
+		}
+
 		if (psr_sink_support(data->drm_fd, data->debugfs_fd, PSR_MODE_1, NULL) ||
 		    psr_sink_support(data->drm_fd, data->debugfs_fd, PR_MODE, NULL))
 			psr_disable(data->drm_fd, data->debugfs_fd, NULL);
-- 
2.48.1