[PATCH 2/3] phy: zynqmp: use read-modify-write for SERDES scrambler bypass

[Radhey Shyam Pandey]

From: Nava kishore Manne <nava.kishore.manne at amd.com>

xpsgtr_bypass_scrambler_8b10b() used xpsgtr_write_phy() which performs
a full register write, silently clearing any bits beyond the intended
bypass control fields.

Switch to xpsgtr_clr_set_phy() with clr=mask, set=mask to set only
the bypass bits while preserving the remaining bits in each register.

Fixes: 4a33bea00314 ("phy: zynqmp: Add PHY driver for the Xilinx ZynqMP Gigabit Transceiver")
Cc: stable at vger.kernel.org
Signed-off-by: Nava kishore Manne <nava.kishore.manne at amd.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey at amd.com>
---
 drivers/phy/xilinx/phy-zynqmp.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/xilinx/phy-zynqmp.c b/drivers/phy/xilinx/phy-zynqmp.c
index c037d7c13d48..6c56c4df8523 100644
--- a/drivers/phy/xilinx/phy-zynqmp.c
+++ b/drivers/phy/xilinx/phy-zynqmp.c
@@ -505,8 +505,12 @@ static void xpsgtr_lane_set_protocol(struct xpsgtr_phy *gtr_phy)
 /* Bypass (de)scrambler and 8b/10b decoder and encoder. */
 static void xpsgtr_bypass_scrambler_8b10b(struct xpsgtr_phy *gtr_phy)
 {
-	xpsgtr_write_phy(gtr_phy, L0_TM_DIG_6, L0_TM_DIS_DESCRAMBLE_DECODER);
-	xpsgtr_write_phy(gtr_phy, L0_TX_DIG_61, L0_TM_DISABLE_SCRAMBLE_ENCODER);
+	xpsgtr_clr_set_phy(gtr_phy, L0_TM_DIG_6,
+			   L0_TM_DIS_DESCRAMBLE_DECODER,
+			   L0_TM_DIS_DESCRAMBLE_DECODER);
+	xpsgtr_clr_set_phy(gtr_phy, L0_TX_DIG_61,
+			   L0_TM_DISABLE_SCRAMBLE_ENCODER,
+			   L0_TM_DISABLE_SCRAMBLE_ENCODER);
 }
 
 /* DP-specific initialization. */
-- 
2.44.4