drm/amd/display: remove get_position() of underlay

get_position() returns CRTC vertical/horizontal counters,
hence it is not applicable for underlay which is plane and not
attached to one crtc.
This patch hence removes the callback from dce110_tg_v_funcs
and hence fixes a bug in dc_debug.c where in
get_position() for underlay pipe is called un-conditionally.

Witout this patch get_position() is called in case one has
to update underlay plane's data,
since callback implmented with an ASSERT(),
the old_surface_count and new_surface_count mismatches; causing
only one plane update which is not right and also assert makes the
rendering slow.
Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -297,11 +297,16 @@ void context_timing_trace(
 	struct dal_logger *logger =  core_dc->ctx->logger;
 	int h_pos[MAX_PIPES], v_pos[MAX_PIPES];
 	struct crtc_position position;
+	unsigned int underlay_idx = core_dc->res_pool->underlay_pipe_index;
+
 
 	for (i = 0; i < core_dc->res_pool->pipe_count; i++) {
 		struct pipe_ctx *pipe_ctx = &res_ctx->pipe_ctx[i];
-
-		if (pipe_ctx->stream == NULL)
+		/* get_position() returns CRTC vertical/horizontal counter
+		 * hence not applicable for underlay pipe
+		 */
+		if (pipe_ctx->stream == NULL
+				 || pipe_ctx->pipe_idx == underlay_idx)
 			continue;
 
 		pipe_ctx->tg->funcs->get_position(pipe_ctx->tg, &position);

drivers/gpu/drm/amd/display/dc/dce110/dce110_timing_generator_v.c

@@ -570,13 +570,6 @@ static void dce110_timing_generator_v_set_early_control(
 	dm_write_reg(tg->ctx, address, regval);
 }
 
-static void dce110_timing_generator_get_underlay_position(struct timing_generator *tg,
-	struct crtc_position *position)
-{
-	//Should never hit this case
-	ASSERT(false);
-}
-
 static uint32_t dce110_timing_generator_v_get_vblank_counter(struct timing_generator *tg)
 {
 	uint32_t addr = mmCRTCV_STATUS_FRAME_COUNT;
@@ -652,7 +645,7 @@ static const struct timing_generator_funcs dce110_tg_v_funcs = {
 		.enable_crtc = dce110_timing_generator_v_enable_crtc,
 		.disable_crtc = dce110_timing_generator_v_disable_crtc,
 		.is_counter_moving = dce110_timing_generator_v_is_counter_moving,
-		.get_position = dce110_timing_generator_get_underlay_position,
+		.get_position = NULL, /* Not to be implemented for underlay*/
 		.get_frame_count = dce110_timing_generator_v_get_vblank_counter,
 		.set_early_control = dce110_timing_generator_v_set_early_control,
 		.wait_for_state = dce110_timing_generator_v_wait_for_state,