From: Ding Wang <Ding.Wang@amd.com>
Date: Tue, 10 Jan 2017 12:47:37 -0500
Subject: drm/amd/display: Use DTO as clock on DP if not
Git-commit: 0ea9e02af5572323f79b493ec8d6bfa55effb2f7
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

Use DVO as pixel clock for DP before enabling link
PHY. Otherwise, when switching from HDMI passive dongle
to DP on the same connector, the PHY PLL is used as
pixel clock, and CRTC would stop working.

Signed-off-by: Ding Wang <Ding.Wang@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>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c |   25 +++++++++++++++++++++
 1 file changed, 25 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
@@ -61,6 +61,31 @@ void dp_enable_link_phy(
 {
 	struct link_encoder *link_enc = link->link_enc;
 
+	struct pipe_ctx *pipes =
+			link->dc->current_context->res_ctx.pipe_ctx;
+	struct clock_source *dp_cs =
+			link->dc->res_pool->dp_clock_source;
+	unsigned int i;
+	/* If the current pixel clock source is not DTO(happens after
+	 * switching from HDMI passive dongle to DP on the same connector),
+	 * switch the pixel clock source to DTO.
+	 */
+	for (i = 0; i < MAX_PIPES; i++) {
+		if (pipes[i].stream != NULL &&
+			pipes[i].stream->sink != NULL &&
+			pipes[i].stream->sink->link == link) {
+			if (pipes[i].clock_source->id != CLOCK_SOURCE_ID_DP_DTO) {
+				pipes[i].clock_source = dp_cs;
+				pipes[i].pix_clk_params.requested_pix_clk =
+						pipes[i].stream->public.timing.pix_clk_khz;
+				pipes[i].clock_source->funcs->program_pix_clk(
+							pipes[i].clock_source,
+							&pipes[i].pix_clk_params,
+							&pipes[i].pll_settings);
+			}
+		}
+	}
+
 	if (dc_is_dp_sst_signal(signal)) {
 		if (signal == SIGNAL_TYPE_EDP) {
 			link_enc->funcs->power_control(link_enc, true);