drm/amd/display: Fix issue with VLine interrupt not firing

[Why]
We are not correctly handling the wrap around case.
VLine interrupt is relative to position of VUpdate interrupt.

Both VUpdate interrupt and VLine interrupt could possibly
be in front porch or back porch.

[How]
Fix wraparound case by checking for line number that is
greater than the VTOTAL of the OTG timing. In this case,
the interrupt should occur on the next frame.

Also fix some variable naming and remove some dead code.
Signed-off-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn10/dcn10_optc.c

@@ -102,14 +102,6 @@ static uint32_t get_start_vline(struct timing_generator *optc, const struct dc_c
 	patched_crtc_timing = *dc_crtc_timing;
 	optc1_apply_front_porch_workaround(optc, &patched_crtc_timing);
 
-	vesa_sync_start = patched_crtc_timing.h_addressable +
-			patched_crtc_timing.h_border_right +
-			patched_crtc_timing.h_front_porch;
-
-	asic_blank_end = patched_crtc_timing.h_total -
-			vesa_sync_start -
-			patched_crtc_timing.h_border_left;
-
 	vesa_sync_start = patched_crtc_timing.v_addressable +
 			patched_crtc_timing.v_border_bottom +
 			patched_crtc_timing.v_front_porch;
@@ -119,10 +111,8 @@ static uint32_t get_start_vline(struct timing_generator *optc, const struct dc_c
 			patched_crtc_timing.v_border_top);
 
 	vertical_line_start = asic_blank_end - optc->dlg_otg_param.vstartup_start + 1;
-	if (vertical_line_start < 0) {
-		ASSERT(0);
+	if (vertical_line_start < 0)
 		vertical_line_start = 0;
-	}
 
 	return vertical_line_start;
 }
@@ -143,7 +133,7 @@ void optc1_program_vline_interrupt(
 
 	uint32_t vsync_line = get_start_vline(optc, dc_crtc_timing);
 	uint32_t start_line = 0;
-	uint32_t endLine = 0;
+	uint32_t end_line = 0;
 
 	if (req_delta_lines != 0)
 		req_delta_lines--;
@@ -153,14 +143,17 @@ void optc1_program_vline_interrupt(
 	else
 		start_line = vsync_line - req_delta_lines;
 
-	endLine = start_line + 2;
+	end_line = start_line + 2;
+
+	if (start_line >= dc_crtc_timing->v_total)
+		start_line = start_line % dc_crtc_timing->v_total;
 
-	if (endLine >= dc_crtc_timing->v_total)
-		endLine = 2;
+	if (end_line >= dc_crtc_timing->v_total)
+		end_line = end_line % dc_crtc_timing->v_total;
 
 	REG_SET_2(OTG_VERTICAL_INTERRUPT0_POSITION, 0,
 			OTG_VERTICAL_INTERRUPT0_LINE_START, start_line,
-			OTG_VERTICAL_INTERRUPT0_LINE_END, endLine);
+			OTG_VERTICAL_INTERRUPT0_LINE_END, end_line);
 }
 
 /**