disp: msm: sde: consider max of actual and default prefill lines

In transfer-time calculation remove fixed prefill lines assumption
and consider max of default prefill lines, prefill lines
specified from the panel timing info and Vtotal. For panels with
higher porches exceeding default prefill lines, alternate framedrops
can occur if transfer-time exceeds RSC static waketup time
as actual prefill lines are considered in RSC static wakeup timer
calculation. This change ensures transfer-time is within
RSC static wakeup time.

Change-Id: Ic489d69cf99cfb6750e871c7fc8197243f61acf3
Signed-off-by: Narendra Muppalla <[email protected]>

msm/dsi/dsi_panel.c

@@ -4014,6 +4014,7 @@ void dsi_panel_calc_dsi_transfer_time(struct dsi_host_common_cfg *config,
 	struct dsi_mode_info *timing = &mode->timing;
 	struct dsi_display_mode *display_mode;
 	u32 jitter_numer, jitter_denom, prefill_lines;
+	u32 default_prefill_lines, actual_prefill_lines, vtotal;
 	u32 min_threshold_us, prefill_time_us, max_transfer_us, packet_overhead;
 	u16 bpp;
 
@@ -4077,11 +4078,15 @@ void dsi_panel_calc_dsi_transfer_time(struct dsi_host_common_cfg *config,
 	 * Increase the prefill_lines proportionately as recommended
 	 * 40lines for 60fps, 60 for 90fps, 120lines for 120fps, and so on.
 	 */
-	prefill_lines = mult_frac(MIN_PREFILL_LINES,
-			timing->refresh_rate, 60);
+	default_prefill_lines = mult_frac(MIN_PREFILL_LINES, timing->refresh_rate, 60);
 
-	prefill_time_us = mult_frac(frame_time_us, prefill_lines,
-			(timing->v_active));
+	actual_prefill_lines = timing->v_back_porch + timing->v_front_porch + timing->v_sync_width;
+	vtotal = actual_prefill_lines + timing->v_active;
+
+	/* consider the max of default prefill lines and actual prefill lines */
+	prefill_lines = max(actual_prefill_lines, default_prefill_lines);
+
+	prefill_time_us = mult_frac(frame_time_us, prefill_lines, vtotal);
 
 	min_threshold_us = min_threshold_us + prefill_time_us;