[PATCH 5.4 045/147] drm/amd/display: check if REFCLK_CNTL register is present

[Greg Kroah-Hartman]

From: Dmytro Laktyushkin <Dmytro.Laktyushkin@xxxxxxx>

[ Upstream commit 3159d41db3a04330c31ece32f8b29752fc114848 ]

Check before programming the register since it isn't present on
all IPs using this code.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@xxxxxxx>
Reviewed-by: Eric Bernstein <Eric.Bernstein@xxxxxxx>
Acked-by: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
index e933f6a369f92..083c42e521f5c 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn20/dcn20_hwseq.c
@@ -2015,7 +2015,8 @@ static void dcn20_fpga_init_hw(struct dc *dc)
 
 	REG_UPDATE(DCHUBBUB_GLOBAL_TIMER_CNTL, DCHUBBUB_GLOBAL_TIMER_REFDIV, 2);
 	REG_UPDATE(DCHUBBUB_GLOBAL_TIMER_CNTL, DCHUBBUB_GLOBAL_TIMER_ENABLE, 1);
-	REG_WRITE(REFCLK_CNTL, 0);
+	if (REG(REFCLK_CNTL))
+		REG_WRITE(REFCLK_CNTL, 0);
 	//
 
 
-- 
2.20.1