[Intel-gfx] [PATCH 2/2] i915/debug: Expose Max BPC info via debugfs

[Bhanuprakash Modem]

[Why]
It's useful to know the max supported panel BPC for IGT testing.

[How]
Expose the max supported BPC for the panel via a debugfs file on the
connector, "output_bpc".

Example usage: cat /sys/kernel/debug/dri/0/DP-1/output_bpc

Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 .../drm/i915/display/intel_display_debugfs.c    | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index 3644752cc5ec..0877d029af77 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -2185,6 +2185,20 @@ static const struct file_operations i915_dsc_fec_support_fops = {
 	.write = i915_dsc_fec_support_write
 };
 
+/*
+ * Returns the maximum output bpc for the connector.
+ * Example usage: cat /sys/kernel/debug/dri/0/DP-1/output_bpc
+ */
+static int output_bpc_show(struct seq_file *m, void *data)
+{
+	struct drm_connector *connector = m->private;
+
+	seq_printf(m, "Maximum: %u\n", connector->display_info.bpc);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(output_bpc);
+
 /**
  * intel_connector_debugfs_add - add i915 specific connector debugfs files
  * @connector: pointer to a registered drm_connector
@@ -2235,5 +2249,8 @@ int intel_connector_debugfs_add(struct drm_connector *connector)
 		debugfs_create_file("i915_lpsp_capability", 0444, root,
 				    connector, &i915_lpsp_capability_fops);
 
+	debugfs_create_file("output_bpc", S_IRUGO, root,
+			connector, &output_bpc_fops);
+
 	return 0;
 }
-- 
2.20.1