[PATCH 4.18 026/228] drm/amd/display: fix use of uninitialized memory

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wesley Chalmers <Wesley.Chalmers@xxxxxxx>

[ Upstream commit f3e077d95ca0a016fdf3d6b1e97a9910dfdaff17 ]

DML does not calculate chroma values for RQ when surface is not YUV, but DC
will unconditionally use the uninitialized values for HW programming.
This does not cause visual corruption since HW will ignore garbage chroma
values when surface is not YUV, but causes presubmission tests to fail
golden value comparison.

Signed-off-by: Wesley Chalmers <Wesley.Chalmers@xxxxxxx>
Signed-off-by: Eryk Brol <eryk.brol@xxxxxxx>
Reviewed-by: Wenjing Liu <Wenjing.Liu@xxxxxxx>
Acked-by: Harry Wentland <harry.wentland@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dml1_display_rq_dlg_calc.c
@@ -239,6 +239,8 @@ void dml1_extract_rq_regs(
 	extract_rq_sizing_regs(mode_lib, &(rq_regs->rq_regs_l), rq_param.sizing.rq_l);
 	if (rq_param.yuv420)
 		extract_rq_sizing_regs(mode_lib, &(rq_regs->rq_regs_c), rq_param.sizing.rq_c);
+	else
+		memset(&(rq_regs->rq_regs_c), 0, sizeof(rq_regs->rq_regs_c));
 
 	rq_regs->rq_regs_l.swath_height = dml_log2(rq_param.dlg.rq_l.swath_height);
 	rq_regs->rq_regs_c.swath_height = dml_log2(rq_param.dlg.rq_c.swath_height);