disp: msm: dp: account for fec overhead during bpp determination

When calculating the maximum bpp that can be supported for the
link configuration and mode, currently the driver is not
accounting for the FEC overhead. When FEC is enabled, the
link bandwidth available for the video stream is reduced and
therefore it needs to be included in the calculation.

Change-Id: I41a664d739f369b17cff2ced7f88f5e90ee196f4
Signed-off-by: Rajkumar Subbiah <rsubbia@codeaurora.org>

msm/dp/dp_panel.c

@@ -1795,7 +1795,8 @@ static u32 dp_panel_get_supported_bpp(struct dp_panel *dp_panel,
 	struct dp_panel_private *panel;
 	const u32 max_supported_bpp = 30;
 	u32 min_supported_bpp = 18;
-	u32 bpp = 0, data_rate_khz = 0;
+	u32 bpp = 0, link_bitrate = 0, mode_bitrate;
+	s64 rate_fp = 0;
 
 	panel = container_of(dp_panel, struct dp_panel_private, dp_panel);
 
@@ -1806,25 +1807,27 @@ static u32 dp_panel_get_supported_bpp(struct dp_panel *dp_panel,
 
 	link_params = &panel->link->link_params;
 
-	data_rate_khz = link_params->lane_count *
-		drm_dp_bw_code_to_link_rate(link_params->bw_code) * 8;
+	rate_fp = drm_int2fixp(drm_dp_bw_code_to_link_rate(link_params->bw_code) *
+			link_params->lane_count *  8);
+
+	if (dp_panel->fec_en)
+		rate_fp = drm_fixp_div(rate_fp, dp_panel->fec_overhead_fp);
+
+	link_bitrate = drm_fixp2int(rate_fp);
 
 	for (; bpp > min_supported_bpp; bpp -= 6) {
 		if (dp_panel->dsc_en) {
-			if (bpp == 36 && !(dp_panel->sink_dsc_caps.color_depth
-					& DP_DSC_12_BPC))
+			if (bpp == 30 && !(dp_panel->sink_dsc_caps.color_depth & DP_DSC_10_BPC))
 				continue;
-			else if (bpp == 30 &&
-					!(dp_panel->sink_dsc_caps.color_depth &
-					DP_DSC_10_BPC))
-				continue;
-			else if (bpp == 24 &&
-					!(dp_panel->sink_dsc_caps.color_depth &
-					DP_DSC_8_BPC))
+			else if (bpp == 24 && !(dp_panel->sink_dsc_caps.color_depth & DP_DSC_8_BPC))
 				continue;
+
+			mode_bitrate = mult_frac(mode_pclk_khz, bpp, 3);
+		} else {
+			mode_bitrate = mode_pclk_khz * bpp;
 		}
 
-		if (mode_pclk_khz * bpp <= data_rate_khz)
+		if (mode_bitrate <= link_bitrate)
 			break;
 	}