drm/amd/display: Fix negative cursor pos programming (v2)

[Why]
If the cursor pos passed from DM is less than the plane_state->dst_rect
top left corner then the unsigned cursor pos wraps around to a large
positive number since cursor pos is a u32.

There was an attempt to guard against this in hubp1_cursor_set_position
by checking the src_x_offset and src_y_offset and offseting the
cursor hotspot within hubp1_cursor_set_position.

However, the cursor position itself is still being programmed
incorrectly as a large value.

This manifests itself visually as the cursor disappearing or containing
strange artifacts near the middle of the screen on raven.

[How]
Don't subtract the destination rect top left corner from the pos but
add it to the hotspot instead. This happens before the pos gets
passed into hubp1_cursor_set_position.

This achieves the same result but avoids the subtraction wrap around.
With this fix the original cursor programming logic can be used again.

v2: add hunk that got dropped accidently when this patch was originally
committed. (Alex)
Fixes: 0921c41e1902831 ("drm/amd/display: Fix negative cursor pos programming")

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Murton Liu <Murton.Liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 2 insertions, 21 deletions

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubp.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubp.c
index 683829466a44..0ba68d41b9c3 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubp.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubp.c
@@ -1150,28 +1150,9 @@ void hubp1_cursor_set_position(
 	REG_UPDATE(CURSOR_CONTROL,
 			CURSOR_ENABLE, cur_en);
 
-	//account for cases where we see negative offset relative to overlay plane
-	if (src_x_offset < 0 && src_y_offset < 0) {
-		REG_SET_2(CURSOR_POSITION, 0,
-			CURSOR_X_POSITION, 0,
-			CURSOR_Y_POSITION, 0);
-		x_hotspot -= src_x_offset;
-		y_hotspot -= src_y_offset;
-	} else if (src_x_offset < 0) {
-		REG_SET_2(CURSOR_POSITION, 0,
-			CURSOR_X_POSITION, 0,
-			CURSOR_Y_POSITION, pos->y);
-		x_hotspot -= src_x_offset;
-	} else if (src_y_offset < 0) {
-		REG_SET_2(CURSOR_POSITION, 0,
+	REG_SET_2(CURSOR_POSITION, 0,
 			CURSOR_X_POSITION, pos->x,
-			CURSOR_Y_POSITION, 0);
-		y_hotspot -= src_y_offset;
-	} else {
-		REG_SET_2(CURSOR_POSITION, 0,
-				CURSOR_X_POSITION, pos->x,
-				CURSOR_Y_POSITION, pos->y);
-	}
+			CURSOR_Y_POSITION, pos->y);
 
 	REG_SET_2(CURSOR_HOT_SPOT, 0,
 			CURSOR_HOT_SPOT_X, x_hotspot,