linux-kernel - [PATCH AUTOSEL 4.20 32/60] drm/amd/display: Fix negative cursor pos programming

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Date:   Wed, 13 Mar 2019 15:09:53 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.20 32/60] drm/amd/display: Fix negative cursor pos programming

From: Nicholas Kazlauskas <nicholas.kazlauskas@....com>

[ Upstream commit 0921c41e19028314830b33daa681e46b46477c5e ]

[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.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@....com>
Reviewed-by: Charlene Liu <Charlene.Liu@....com>
Acked-by: Leo Li <sunpeng.li@....com>
Acked-by: Murton Liu <Murton.Liu@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
index 220ba828748d..5bc214ce5227 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hw_sequencer.c
@@ -2654,8 +2654,8 @@ static void dcn10_set_cursor_position(struct pipe_ctx *pipe_ctx)
 		.mirror = pipe_ctx->plane_state->horizontal_mirror
 	};

-	pos_cpy.x -= pipe_ctx->plane_state->dst_rect.x;
-	pos_cpy.y -= pipe_ctx->plane_state->dst_rect.y;
+	pos_cpy.x_hotspot += pipe_ctx->plane_state->dst_rect.x;
+	pos_cpy.y_hotspot += pipe_ctx->plane_state->dst_rect.y;

 	if (pipe_ctx->plane_state->address.type
 			== PLN_ADDR_TYPE_VIDEO_PROGRESSIVE)
-- 
2.19.1