[PATCH 5.5 246/257] drm/bridge: analogix-anx78xx: Fix drm_dp_link helper removal

[Greg Kroah-Hartman]

From: Torsten Duwe <duwe@xxxxxx>

[ Upstream commit 3e138a63d6674a4567a018a31e467567c40b14d5 ]

drm_dp_link_rate_to_bw_code and ...bw_code_to_link_rate simply divide by
and multiply with 27000, respectively. Avoid an overflow in the u8 dpcd[0]
and the multiply+divide alltogether.

Signed-off-by: Torsten Duwe <duwe@xxxxxx>
Fixes: ff1e8fb68ea0 ("drm/bridge: analogix-anx78xx: Avoid drm_dp_link helpers")
Cc: Thierry Reding <treding@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Cc: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
Cc: Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Jonas Karlman <jonas@xxxxxxxxx>
Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v5.5+
Reviewed-by: Thierry Reding <treding@xxxxxxxxxx>
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20200218155744.9675368BE1@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/gpu/drm/bridge/analogix-anx78xx.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix-anx78xx.c
index 274989f96a916..914263a1afab4 100644
--- a/drivers/gpu/drm/bridge/analogix-anx78xx.c
+++ b/drivers/gpu/drm/bridge/analogix-anx78xx.c
@@ -866,10 +866,9 @@ static int anx78xx_dp_link_training(struct anx78xx *anx78xx)
 	if (err)
 		return err;
 
-	dpcd[0] = drm_dp_max_link_rate(anx78xx->dpcd);
-	dpcd[0] = drm_dp_link_rate_to_bw_code(dpcd[0]);
 	err = regmap_write(anx78xx->map[I2C_IDX_TX_P0],
-			   SP_DP_MAIN_LINK_BW_SET_REG, dpcd[0]);
+			   SP_DP_MAIN_LINK_BW_SET_REG,
+			   anx78xx->dpcd[DP_MAX_LINK_RATE]);
 	if (err)
 		return err;
 
-- 
2.20.1