drm/amd/display: Add tracing to dc

[Why]
Tracing is a useful and cheap debug functionality

[How]
This creates a new trace system amdgpu_dm, currently with
three trace events

amdgpu_dc_rreg and amdgpu_dc_wreg report the address and value
of any dc register reads and writes

amdgpu_dc_performance requires at least one of those two to be
enabled.  It counts the register reads and writes since the
last entry

v2: Don't check for NULL before kfree

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dc_types.h b/drivers/gpu/drm/amd/display/dc/dc_types.h
index 91911ef8d746..0b20ae23f169 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_types.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_types.h
@@ -73,10 +73,18 @@ struct hw_asic_id {
 	void *atombios_base_address;
 };
 
+struct dc_perf_trace {
+	unsigned long read_count;
+	unsigned long write_count;
+	unsigned long last_entry_read;
+	unsigned long last_entry_write;
+};
+
 struct dc_context {
 	struct dc *dc;
 
 	void *driver_context; /* e.g. amdgpu_device */
+	struct dc_perf_trace *perf_trace;
 	void *cgs_device;
 
 	enum dce_environment dce_environment;