drm/amd/display: Update Cursor request mode to the beginning prefetch always

[Why]
The double buffer cursor registers is updated by the cursor
vupdate event. There is a gap between vupdate and cursor data
fetch if cursor fetch data reletive to cursor position.
Cursor corruption will happen if we update the cursor surface
in this gap.

[How]
Modify the cursor request mode to the beginning prefetch always
and avoid wraparound calculation issues.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Zhikai Zhai <zhikai.zhai@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Zhikai Zhai

drivers/gpu/drm/amd/display/dc/hubp/dcn31/dcn31_hubp.c

@@ -44,7 +44,7 @@ void hubp31_set_unbounded_requesting(struct hubp *hubp, bool enable)
 	struct dcn20_hubp *hubp2 = TO_DCN20_HUBP(hubp);
 
 	REG_UPDATE(DCHUBP_CNTL, HUBP_UNBOUNDED_REQ_MODE, enable);
-	REG_UPDATE(CURSOR_CONTROL, CURSOR_REQ_MODE, enable);
+	REG_UPDATE(CURSOR_CONTROL, CURSOR_REQ_MODE, 1);
 }
 
 void hubp31_soft_reset(struct hubp *hubp, bool reset)

drivers/gpu/drm/amd/display/dc/hwss/dcn10/dcn10_hwseq.c

@@ -1993,34 +1993,30 @@ static void delay_cursor_until_vupdate(struct dc *dc, struct pipe_ctx *pipe_ctx)
 	dc->hwss.get_position(&pipe_ctx, 1, &position);
 	vpos = position.vertical_count;
 
-	/* Avoid wraparound calculation issues */
-	vupdate_start += stream->timing.v_total;
-	vupdate_end += stream->timing.v_total;
-	vpos += stream->timing.v_total;
-
 	if (vpos <= vupdate_start) {
 		/* VPOS is in VACTIVE or back porch. */
 		lines_to_vupdate = vupdate_start - vpos;
-	} else if (vpos > vupdate_end) {
-		/* VPOS is in the front porch. */
-		return;
 	} else {
-		/* VPOS is in VUPDATE. */
-		lines_to_vupdate = 0;
+		lines_to_vupdate = stream->timing.v_total - vpos + vupdate_start;
 	}
 
 	/* Calculate time until VUPDATE in microseconds. */
 	us_per_line =
 		stream->timing.h_total * 10000u / stream->timing.pix_clk_100hz;
 	us_to_vupdate = lines_to_vupdate * us_per_line;
 
+	/* Stall out until the cursor update completes. */
+	if (vupdate_end < vupdate_start)
+		vupdate_end += stream->timing.v_total;
+
+	/* Position is in the range of vupdate start and end*/
+	if (lines_to_vupdate > stream->timing.v_total - vupdate_end + vupdate_start)
+		us_to_vupdate = 0;
+
 	/* 70 us is a conservative estimate of cursor update time*/
 	if (us_to_vupdate > 70)
 		return;
 
-	/* Stall out until the cursor update completes. */
-	if (vupdate_end < vupdate_start)
-		vupdate_end += stream->timing.v_total;
 	us_vupdate = (vupdate_end - vupdate_start + 1) * us_per_line;
 	udelay(us_to_vupdate + us_vupdate);
 }