drm/amd/display: fix is_timing_changed() prototype

Three functions in the amdgpu display driver cause -Wmissing-prototype
warnings:

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_resource.c:1858:6: error: no previous prototype for 'is_timing_changed' [-Werror=missing-prototypes]

is_timing_changed() is actually meant to be a global symbol, but needs
a proper name and prototype.

Fixes: 17ce8a69 ("drm/amd/display: Add dsc pre-validation in atomic check")
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c

@@ -45,8 +45,7 @@
 #endif
 
 #include "dc/dcn20/dcn20_resource.h"
-bool is_timing_changed(struct dc_stream_state *cur_stream,
-		       struct dc_stream_state *new_stream);
+
 #define PEAK_FACTOR_X1000 1006
 
 static ssize_t dm_dp_aux_transfer(struct drm_dp_aux *aux,
@@ -1422,7 +1421,7 @@ int pre_validate_dsc(struct drm_atomic_state *state,
 		struct dc_stream_state *stream = dm_state->context->streams[i];
 
 		if (local_dc_state->streams[i] &&
-		    is_timing_changed(stream, local_dc_state->streams[i])) {
+		    dc_is_timing_changed(stream, local_dc_state->streams[i])) {
 			DRM_INFO_ONCE("crtc[%d] needs mode_changed\n", i);
 		} else {
 			int ind = find_crtc_index_in_state_by_stream(state, stream);

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

@@ -1858,7 +1858,7 @@ bool dc_add_all_planes_for_stream(
 	return add_all_planes_for_stream(dc, stream, &set, 1, context);
 }
 
-bool is_timing_changed(struct dc_stream_state *cur_stream,
+bool dc_is_timing_changed(struct dc_stream_state *cur_stream,
 		       struct dc_stream_state *new_stream)
 {
 	if (cur_stream == NULL)
@@ -1883,7 +1883,7 @@ static bool are_stream_backends_same(
 	if (stream_a == NULL || stream_b == NULL)
 		return false;
 
-	if (is_timing_changed(stream_a, stream_b))
+	if (dc_is_timing_changed(stream_a, stream_b))
 		return false;
 
 	if (stream_a->signal != stream_b->signal)
@@ -3508,7 +3508,7 @@ bool pipe_need_reprogram(
 	if (pipe_ctx_old->stream_res.stream_enc != pipe_ctx->stream_res.stream_enc)
 		return true;
 
-	if (is_timing_changed(pipe_ctx_old->stream, pipe_ctx->stream))
+	if (dc_is_timing_changed(pipe_ctx_old->stream, pipe_ctx->stream))
 		return true;
 
 	if (pipe_ctx_old->stream->dpms_off != pipe_ctx->stream->dpms_off)

drivers/gpu/drm/amd/display/dc/dc.h

@@ -2228,4 +2228,7 @@ void dc_process_dmub_dpia_hpd_int_enable(const struct dc *dc,
 /* Disable acc mode Interfaces */
 void dc_disable_accelerated_mode(struct dc *dc);
 
+bool dc_is_timing_changed(struct dc_stream_state *cur_stream,
+		       struct dc_stream_state *new_stream);
+
 #endif /* DC_INTERFACE_H_ */