drm/i915/display: debugfs entry to list display capabilities

Create a separate debugfs entry to list the display capabilities
IGT can rely on this debugfs entry for tests that depend on
display device and display runtime info for both xe and i915
drivers.

v2: rename the entry to i915_display_capabilities (Chaitanya)
Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231018102723.16915-2-vinod.govindapillai@intel.com

drivers/gpu/drm/i915/display/intel_display_debugfs.c

@@ -642,6 +642,17 @@ static int i915_display_info(struct seq_file *m, void *unused)
 	return 0;
 }
 
+static int i915_display_capabilities(struct seq_file *m, void *unused)
+{
+	struct drm_i915_private *i915 = node_to_i915(m->private);
+	struct drm_printer p = drm_seq_file_printer(m);
+
+	intel_display_device_info_print(DISPLAY_INFO(i915),
+					DISPLAY_RUNTIME_INFO(i915), &p);
+
+	return 0;
+}
+
 static int i915_shared_dplls_info(struct seq_file *m, void *unused)
 {
 	struct drm_i915_private *dev_priv = node_to_i915(m->private);
@@ -1060,6 +1071,7 @@ static const struct drm_info_list intel_display_debugfs_list[] = {
 	{"i915_gem_framebuffer", i915_gem_framebuffer_info, 0},
 	{"i915_power_domain_info", i915_power_domain_info, 0},
 	{"i915_display_info", i915_display_info, 0},
+	{"i915_display_capabilities", i915_display_capabilities, 0},
 	{"i915_shared_dplls_info", i915_shared_dplls_info, 0},
 	{"i915_dp_mst_info", i915_dp_mst_info, 0},
 	{"i915_ddb_info", i915_ddb_info, 0},