drm/amd/display: on dp link lost event toggle dpms for master pipe only

[why]
We mistakenly toggle dpms state for non master pipe when handling
link lost. A non master pipe doesn't connect to a backend. So it is
toggling dpms for non master is undefined and caused NULL pointer
dereference.

[how]
Add helper functions to find an array of active master pipes for current
link and only toggle DPMS for active master pipes connected to the link.
Add assert in case we get called to program dpms with non master pipe.
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/link/accessories/link_dp_cts.c

@@ -27,6 +27,7 @@
 #include "link/protocols/link_dp_training.h"
 #include "link/protocols/link_dp_phy.h"
 #include "link/protocols/link_dp_training_fixed_vs_pe_retimer.h"
+#include "link/link_dpms.h"
 #include "resource.h"
 #include "dm_helpers.h"
 #include "dc_dmub_srv.h"
@@ -77,37 +78,26 @@ void dp_retrain_link_dp_test(struct dc_link *link,
 			struct dc_link_settings *link_setting,
 			bool skip_video_pattern)
 {
-	struct pipe_ctx *pipe;
-	unsigned int i;
+	struct pipe_ctx *pipes[MAX_PIPES];
+	struct dc_state *state = link->dc->current_state;
+	uint8_t count;
+	int i;
 
 	udelay(100);
 
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe->stream != NULL &&
-				pipe->stream->link == link &&
-				!pipe->stream->dpms_off &&
-				!pipe->top_pipe && !pipe->prev_odm_pipe) {
-			link_set_dpms_off(pipe);
-			pipe->link_config.dp_link_settings = *link_setting;
-			update_dp_encoder_resources_for_test_harness(
-					link->dc,
-					pipe->stream->ctx->dc->current_state,
-					pipe);
-		}
-	}
+	link_get_master_pipes_with_dpms_on(link, state, &count, pipes);
 
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe->stream != NULL &&
-				pipe->stream->link == link &&
-				!pipe->stream->dpms_off &&
-				!pipe->top_pipe && !pipe->prev_odm_pipe) {
-			link_set_dpms_on(
-					pipe->stream->ctx->dc->current_state,
-					pipe);
-		}
+	for (i = 0; i < count; i++) {
+		link_set_dpms_off(pipes[i]);
+		pipes[i]->link_config.dp_link_settings = *link_setting;
+		update_dp_encoder_resources_for_test_harness(
+				link->dc,
+				state,
+				pipes[i]);
 	}
+
+	for (i = count-1; i >= 0; i--)
+		link_set_dpms_on(state, pipes[i]);
 }
 
 static void dp_test_send_link_training(struct dc_link *link)

drivers/gpu/drm/amd/display/dc/link/link_detection.c

@@ -30,6 +30,7 @@
  * directly from connected receivers.
  */
 
+#include "link_dpms.h"
 #include "link_detection.h"
 #include "link_hwss.h"
 #include "protocols/link_edp_panel_control.h"
@@ -755,34 +756,6 @@ static void restore_phy_clocks_for_destructive_link_verification(const struct dc
 	clk_mgr_optimize_pwr_state(dc, dc->clk_mgr);
 }
 
-static void set_all_streams_dpms_off_for_link(struct dc_link *link)
-{
-	int i;
-	struct pipe_ctx *pipe_ctx;
-	struct dc_stream_update stream_update;
-	bool dpms_off = true;
-	struct link_resource link_res = {0};
-
-	memset(&stream_update, 0, sizeof(stream_update));
-	stream_update.dpms_off = &dpms_off;
-
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe_ctx = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe_ctx && pipe_ctx->stream && !pipe_ctx->stream->dpms_off &&
-				pipe_ctx->stream->link == link && !pipe_ctx->prev_odm_pipe) {
-			stream_update.stream = pipe_ctx->stream;
-			dc_commit_updates_for_stream(link->ctx->dc, NULL, 0,
-					pipe_ctx->stream, &stream_update,
-					link->ctx->dc->current_state);
-		}
-	}
-
-	/* link can be also enabled by vbios. In this case it is not recorded
-	 * in pipe_ctx. Disable link phy here to make sure it is completely off
-	 */
-	dp_disable_link_phy(link, &link_res, link->connector_signal);
-}
-
 static void verify_link_capability_destructive(struct dc_link *link,
 		struct dc_sink *sink,
 		enum dc_detect_reason reason)
@@ -796,7 +769,7 @@ static void verify_link_capability_destructive(struct dc_link *link,
 	if (dc_is_dp_signal(link->local_sink->sink_signal)) {
 		struct dc_link_settings known_limit_link_setting =
 				dp_get_max_link_cap(link);
-		set_all_streams_dpms_off_for_link(link);
+		link_set_all_streams_dpms_off_for_link(link);
 		dp_verify_link_cap_with_retries(
 				link, &known_limit_link_setting,
 				LINK_TRAINING_MAX_VERIFY_RETRY);

drivers/gpu/drm/amd/display/dc/link/link_dpms.c

@@ -140,12 +140,76 @@ void link_blank_dp_stream(struct dc_link *link, bool hw_init)
 	}
 }
 
+void link_set_all_streams_dpms_off_for_link(struct dc_link *link)
+{
+	struct pipe_ctx *pipes[MAX_PIPES];
+	struct dc_state *state = link->dc->current_state;
+	uint8_t count;
+	int i;
+	struct dc_stream_update stream_update;
+	bool dpms_off = true;
+	struct link_resource link_res = {0};
+
+	memset(&stream_update, 0, sizeof(stream_update));
+	stream_update.dpms_off = &dpms_off;
+
+	link_get_master_pipes_with_dpms_on(link, state, &count, pipes);
+
+	for (i = 0; i < count; i++) {
+		stream_update.stream = pipes[i]->stream;
+		dc_commit_updates_for_stream(link->ctx->dc, NULL, 0,
+				pipes[i]->stream, &stream_update,
+				state);
+	}
+
+	/* link can be also enabled by vbios. In this case it is not recorded
+	 * in pipe_ctx. Disable link phy here to make sure it is completely off
+	 */
+	dp_disable_link_phy(link, &link_res, link->connector_signal);
+}
+
 void link_resume(struct dc_link *link)
 {
 	if (link->connector_signal != SIGNAL_TYPE_VIRTUAL)
 		program_hpd_filter(link);
 }
 
+/* This function returns true if the pipe is used to feed video signal directly
+ * to the link.
+ */
+static bool is_master_pipe_for_link(const struct dc_link *link,
+		const struct pipe_ctx *pipe)
+{
+	return (pipe->stream &&
+			pipe->stream->link &&
+			pipe->stream->link == link &&
+			pipe->top_pipe == NULL &&
+			pipe->prev_odm_pipe == NULL);
+}
+
+/*
+ * This function finds all master pipes feeding to a given link with dpms set to
+ * on in given dc state.
+ */
+void link_get_master_pipes_with_dpms_on(const struct dc_link *link,
+		struct dc_state *state,
+		uint8_t *count,
+		struct pipe_ctx *pipes[MAX_PIPES])
+{
+	int i;
+	struct pipe_ctx *pipe = NULL;
+
+	*count = 0;
+	for (i = 0; i < MAX_PIPES; i++) {
+		pipe = &state->res_ctx.pipe_ctx[i];
+
+		if (is_master_pipe_for_link(link, pipe) &&
+				pipe->stream->dpms_off == false) {
+			pipes[(*count)++] = pipe;
+		}
+	}
+}
+
 static bool get_ext_hdmi_settings(struct pipe_ctx *pipe_ctx,
 		enum engine_id eng_id,
 		struct ext_hdmi_settings *settings)
@@ -2176,6 +2240,8 @@ void link_set_dpms_off(struct pipe_ctx *pipe_ctx)
 	struct dc_link *link = stream->sink->link;
 	struct vpg *vpg = pipe_ctx->stream_res.stream_enc->vpg;
 
+	ASSERT(is_master_pipe_for_link(link, pipe_ctx));
+
 	if (link_is_dp_128b_132b_signal(pipe_ctx))
 		vpg = pipe_ctx->stream_res.hpo_dp_stream_enc->vpg;
 
@@ -2280,6 +2346,8 @@ void link_set_dpms_on(
 	struct vpg *vpg = pipe_ctx->stream_res.stream_enc->vpg;
 	const struct link_hwss *link_hwss = get_link_hwss(link, &pipe_ctx->link_res);
 
+	ASSERT(is_master_pipe_for_link(link, pipe_ctx));
+
 	if (link_is_dp_128b_132b_signal(pipe_ctx))
 		vpg = pipe_ctx->stream_res.hpo_dp_stream_enc->vpg;
 
@@ -2463,4 +2531,3 @@ void link_set_dpms_on(
 		set_avmute(pipe_ctx, false);
 	}
 }
-

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

@@ -32,4 +32,9 @@ bool link_set_dsc_pps_packet(struct pipe_ctx *pipe_ctx,
 struct fixed31_32 link_calculate_sst_avg_time_slots_per_mtp(
 		const struct dc_stream_state *stream,
 		const struct dc_link *link);
+void link_set_all_streams_dpms_off_for_link(struct dc_link *link);
+void link_get_master_pipes_with_dpms_on(const struct dc_link *link,
+		struct dc_state *state,
+		uint8_t *count,
+		struct pipe_ctx *pipes[MAX_PIPES]);
 #endif /* __DC_LINK_DPMS_H__ */

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_irq_handler.c

@@ -34,6 +34,7 @@
 #include "link_dp_training.h"
 #include "link_dp_capability.h"
 #include "link/accessories/link_dp_trace.h"
+#include "link/link_dpms.h"
 #include "dm_helpers.h"
 
 #define DC_LOGGER_INIT(logger)
@@ -175,40 +176,27 @@ static bool handle_hpd_irq_psr_sink(struct dc_link *link)
 
 void dc_link_dp_handle_link_loss(struct dc_link *link)
 {
+	struct pipe_ctx *pipes[MAX_PIPES];
+	struct dc_state *state = link->dc->current_state;
+	uint8_t count;
 	int i;
-	struct pipe_ctx *pipe_ctx;
 
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe_ctx = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe_ctx && pipe_ctx->stream && pipe_ctx->stream->link == link)
-			break;
-	}
+	link_get_master_pipes_with_dpms_on(link, state, &count, pipes);
 
-	if (pipe_ctx == NULL || pipe_ctx->stream == NULL)
-		return;
+	for (i = 0; i < count; i++)
+		link_set_dpms_off(pipes[i]);
 
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe_ctx = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe_ctx && pipe_ctx->stream && !pipe_ctx->stream->dpms_off &&
-				pipe_ctx->stream->link == link && !pipe_ctx->prev_odm_pipe)
-			link_set_dpms_off(pipe_ctx);
-	}
-
-	for (i = 0; i < MAX_PIPES; i++) {
-		pipe_ctx = &link->dc->current_state->res_ctx.pipe_ctx[i];
-		if (pipe_ctx && pipe_ctx->stream && !pipe_ctx->stream->dpms_off
-				&& pipe_ctx->stream->link == link && !pipe_ctx->prev_odm_pipe) {
-			// Always use max settings here for DP 1.4a LL Compliance CTS
-			if (link->is_automated) {
-				pipe_ctx->link_config.dp_link_settings.lane_count =
-						link->verified_link_cap.lane_count;
-				pipe_ctx->link_config.dp_link_settings.link_rate =
-						link->verified_link_cap.link_rate;
-				pipe_ctx->link_config.dp_link_settings.link_spread =
-						link->verified_link_cap.link_spread;
-			}
-			link_set_dpms_on(link->dc->current_state, pipe_ctx);
+	for (i = count - 1; i >= 0; i--) {
+		// Always use max settings here for DP 1.4a LL Compliance CTS
+		if (link->is_automated) {
+			pipes[i]->link_config.dp_link_settings.lane_count =
+					link->verified_link_cap.lane_count;
+			pipes[i]->link_config.dp_link_settings.link_rate =
+					link->verified_link_cap.link_rate;
+			pipes[i]->link_config.dp_link_settings.link_spread =
+					link->verified_link_cap.link_spread;
 		}
+		link_set_dpms_on(link->dc->current_state, pipes[i]);
 	}
 }