[PATCH i-g-t 3/9] lib/igt_kms: add function to get max link rate/lane count

[Kunal Joshi <kunal1.joshi@intel.com>]

[1] allows to get max link rate/lane count for a particular
connector. add functions to retrieve data via newly
exposed interface

[1] https://patchwork.freedesktop.org/patch/594763/?series=133624&rev=3

Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
---
 lib/igt_kms.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  2 ++
 2 files changed, 58 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index 54e982c81..922982ef0 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -6757,3 +6757,59 @@ enum dp_lane_count igt_get_dp_lane_count_set_for_output(int drm_fd, igt_output_t
 
 	return lane_count;
 }
+
+/**
+ * igt_get_dp_max_link_rate:
+ * @drm_fd: A drm file descriptor
+ *
+ * Get the max link rate supported by sink.
+ *
+ * Returns: Max link rate supported by sink.
+ */
+enum dp_link_rate igt_get_dp_max_link_rate(int drm_fd, igt_output_t *output)
+{
+	char buf[512];
+	int dir, res;
+	int max_link_rate = DP_LINK_RATE_2000000;
+
+	igt_require_f(output->name, "Invalid output");
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_DIRECTORY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+				 igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, "i915_dp_max_link_rate",
+								  buf, sizeof(buf));
+	close(dir);
+	igt_require_f(res > 0, "Couldn't read i915_dp_max_link_rate");
+
+	igt_assert(sscanf(buf, "%d", &max_link_rate) == 1);
+
+	return max_link_rate;
+}
+
+/**
+ * igt_get_dp_max_lane_count:
+ * @drm_fd: A drm file descriptor
+ *
+ * Get the max lane count supported by sink.
+ *
+ * Returns: Max lane count supported by sink.
+ */
+enum dp_lane_count igt_get_dp_max_lane_count(int drm_fd, igt_output_t *output)
+{
+	char buf[512];
+	int dir, res;
+	int max_lane_count = DP_LANE_COUNT_4;
+
+	igt_require_f(output->name, "Invalid output");
+	dir = igt_debugfs_connector_dir(drm_fd, output->name, O_RDONLY);
+	igt_assert_f(dir >= 0, "Failed to open debugfs dir for connector %s\n",
+				 igt_output_name(output));
+	res = igt_debugfs_simple_read(dir, "i915_dp_max_lane_count",
+								  buf, sizeof(buf));
+	close(dir);
+	igt_require(res > 0);
+
+	igt_assert(sscanf(buf, "%d", &max_lane_count) == 1);
+
+	return max_lane_count;
+}
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 43bc238ae..794059e3d 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1260,5 +1260,7 @@ int get_num_scalers(int drm_fd, enum pipe pipe);
 void read_link_rates(int drm_fd, uint64_t *link_rates, int *num_rates, igt_output_t *output);
 enum dp_link_rate igt_get_dp_link_rate_set_for_output(int drm_fd, igt_output_t *output);
 enum dp_lane_count igt_get_dp_lane_count_set_for_output(int drm_fd, igt_output_t *output);
+enum dp_link_rate igt_get_dp_max_link_rate(int drm_fd, igt_output_t *output);
+enum dp_lane_count igt_get_dp_max_lane_count(int drm_fd, igt_output_t *output);
 
 #endif /* __IGT_KMS_H__ */
-- 
2.43.0