drm/amd/display: Check if clock source in use before disabling

[why]
We are disabling clock source while other pipes are still using
it, because we don't verify the number of pipes that share it.

[how]
- Adding a function in resources to return the number of pipes
sharing the clock source.
- Checking that no one is sharing the clock source before disabling

Signed-off-by: Mikita Lipski <mikita.lipski@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>
Cc: stable@vger.kernel.org

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

@@ -268,24 +268,30 @@ bool resource_construct(
 
 	return true;
 }
+static int find_matching_clock_source(
+		const struct resource_pool *pool,
+		struct clock_source *clock_source)
+{
+
+	int i;
 
+	for (i = 0; i < pool->clk_src_count; i++) {
+		if (pool->clock_sources[i] == clock_source)
+			return i;
+	}
+	return -1;
+}
 
 void resource_unreference_clock_source(
 		struct resource_context *res_ctx,
 		const struct resource_pool *pool,
 		struct clock_source *clock_source)
 {
-	int i;
-
-	for (i = 0; i < pool->clk_src_count; i++) {
-		if (pool->clock_sources[i] != clock_source)
-			continue;
+	int i = find_matching_clock_source(pool, clock_source);
 
+	if (i > -1)
 		res_ctx->clock_source_ref_count[i]--;
 
-		break;
-	}
-
 	if (pool->dp_clock_source == clock_source)
 		res_ctx->dp_clock_source_ref_count--;
 }
@@ -295,19 +301,31 @@ void resource_reference_clock_source(
 		const struct resource_pool *pool,
 		struct clock_source *clock_source)
 {
-	int i;
-	for (i = 0; i < pool->clk_src_count; i++) {
-		if (pool->clock_sources[i] != clock_source)
-			continue;
+	int i = find_matching_clock_source(pool, clock_source);
 
+	if (i > -1)
 		res_ctx->clock_source_ref_count[i]++;
-		break;
-	}
 
 	if (pool->dp_clock_source == clock_source)
 		res_ctx->dp_clock_source_ref_count++;
 }
 
+int resource_get_clock_source_reference(
+		struct resource_context *res_ctx,
+		const struct resource_pool *pool,
+		struct clock_source *clock_source)
+{
+	int i = find_matching_clock_source(pool, clock_source);
+
+	if (i > -1)
+		return res_ctx->clock_source_ref_count[i];
+
+	if (pool->dp_clock_source == clock_source)
+		return res_ctx->dp_clock_source_ref_count;
+
+	return -1;
+}
+
 bool resource_are_streams_timing_synchronizable(
 	struct dc_stream_state *stream1,
 	struct dc_stream_state *stream2)

drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c

@@ -1908,7 +1908,9 @@ static void dce110_reset_hw_ctx_wrap(
 			pipe_ctx_old->plane_res.mi->funcs->free_mem_input(
 					pipe_ctx_old->plane_res.mi, dc->current_state->stream_count);
 
-			if (old_clk)
+			if (old_clk && 0 == resource_get_clock_source_reference(&context->res_ctx,
+										dc->res_pool,
+										old_clk))
 				old_clk->funcs->cs_power_down(old_clk);
 
 			dc->hwss.disable_plane(dc, pipe_ctx_old);

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

@@ -103,6 +103,11 @@ void resource_reference_clock_source(
 		const struct resource_pool *pool,
 		struct clock_source *clock_source);
 
+int resource_get_clock_source_reference(
+		struct resource_context *res_ctx,
+		const struct resource_pool *pool,
+		struct clock_source *clock_source);
+
 bool resource_are_streams_timing_synchronizable(
 		struct dc_stream_state *stream1,
 		struct dc_stream_state *stream2);