drm/i915/lobf: Add debug interface for lobf

Add an interface in debugfs which will help in debugging LOBF
feature.

v1: Initial version.
v2:
- Remove FORCE_EN flag. [Jouni]
- Change prefix from I915 to INTEL. [Jani]
- Use u8 instead of bool for lobf-debug flag. [Jani]
v3:
- Use intel_connector instead of display. [Jani]
- Remove edp connector check as it was already present
in caller function. [Jani]
- Remove loop of searching edp encoder which is directly
accessible from intel_connector. [Jani]
v4:
- Simplify alpm debug to bool instead of bit-mask. [Jani]
v5:
- Remove READ_ONCE(). [Jani]
- Modify variable name to *_disable_*. [Jouni]
v6: Improved debug print. [Jouni]

Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://lore.kernel.org/r/20250423092334.2294483-8-animesh.manna@intel.com

2 files changed, 35 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c b/drivers/gpu/drm/i915/display/intel_alpm.c
index d38e729682ce..269768c95a3d 100644
--- a/drivers/gpu/drm/i915/display/intel_alpm.c
+++ b/drivers/gpu/drm/i915/display/intel_alpm.c
@@ -278,6 +278,11 @@ void intel_alpm_lobf_compute_config(struct intel_dp *intel_dp,
 	int waketime_in_lines, first_sdp_position;
 	int context_latency, guardband;
 
+	if (intel_dp->alpm_parameters.lobf_disable_debug) {
+		drm_dbg_kms(display->drm, "LOBF is disabled by debug flag\n");
+		return;
+	}
+
 	if (!intel_dp_is_edp(intel_dp))
 		return;
 
@@ -476,6 +481,32 @@ out:
 
 DEFINE_SHOW_ATTRIBUTE(i915_edp_lobf_info);
 
+static int
+i915_edp_lobf_debug_get(void *data, u64 *val)
+{
+	struct intel_connector *connector = data;
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+
+	*val = intel_dp->alpm_parameters.lobf_disable_debug;
+
+	return 0;
+}
+
+static int
+i915_edp_lobf_debug_set(void *data, u64 val)
+{
+	struct intel_connector *connector = data;
+	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
+
+	intel_dp->alpm_parameters.lobf_disable_debug = val;
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(i915_edp_lobf_debug_fops,
+			i915_edp_lobf_debug_get, i915_edp_lobf_debug_set,
+			"%llu\n");
+
 void intel_alpm_lobf_debugfs_add(struct intel_connector *connector)
 {
 	struct intel_display *display = to_intel_display(connector);
@@ -485,6 +516,9 @@ void intel_alpm_lobf_debugfs_add(struct intel_connector *connector)
 	    connector->base.connector_type != DRM_MODE_CONNECTOR_eDP)
 		return;
 
+	debugfs_create_file("i915_edp_lobf_debug", 0644, root,
+			    connector, &i915_edp_lobf_debug_fops);
+
 	debugfs_create_file("i915_edp_lobf_info", 0444, root,
 			    connector, &i915_edp_lobf_info_fops);
 }
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index f28edaad3270..457a2fb9efa8 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -1815,6 +1815,7 @@ struct intel_dp {
 		u8 aux_less_wake_lines;
 		u8 silence_period_sym_clocks;
 		u8 lfps_half_cycle_num_of_syms;
+		bool lobf_disable_debug;
 	} alpm_parameters;
 
 	u8 alpm_dpcd;