linux-kernel - [PATCH RESEND 3/3] phy: rockchip: samsung-hdptx: Prevent Inter-Pair Skew from exceeding the limits

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Message-Id: <20251028-phy-hdptx-fixes-v1-3-ecc642a59d94@collabora.com>
Date: Tue, 28 Oct 2025 10:00:56 +0200
From: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To: Vinod Koul <vkoul@...nel.org>, 
 Kishon Vijay Abraham I <kishon@...nel.org>, 
 Heiko Stuebner <heiko@...ech.de>, Dmitry Baryshkov <lumag@...nel.org>, 
 Algea Cao <algea.cao@...k-chips.com>
Cc: kernel@...labora.com, linux-phy@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org, 
 linux-kernel@...r.kernel.org
Subject: [PATCH RESEND 3/3] phy: rockchip: samsung-hdptx: Prevent
 Inter-Pair Skew from exceeding the limits

Fixup PHY deskew FIFO to prevent the phase of D2 lane going ahead of
other lanes.  It's worth noting this might only happen when dealing with
HDMI 2.0 rates.

Fixes: 553be2830c5f ("phy: rockchip: Add Samsung HDMI/eDP Combo PHY driver")
Co-developed-by: Algea Cao <algea.cao@...k-chips.com>
Signed-off-by: Algea Cao <algea.cao@...k-chips.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
---
 drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
index 8ba9b53c2309..29de2f7bdae8 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
@@ -668,13 +668,9 @@ static const struct reg_sequence rk_hdtpx_common_lane_init_seq[] = {
 
 static const struct reg_sequence rk_hdtpx_tmds_lane_init_seq[] = {
 	REG_SEQ0(LANE_REG(0312), 0x00),
-	REG_SEQ0(LANE_REG(031e), 0x00),
 	REG_SEQ0(LANE_REG(0412), 0x00),
-	REG_SEQ0(LANE_REG(041e), 0x00),
 	REG_SEQ0(LANE_REG(0512), 0x00),
-	REG_SEQ0(LANE_REG(051e), 0x00),
 	REG_SEQ0(LANE_REG(0612), 0x00),
-	REG_SEQ0(LANE_REG(061e), 0x08),
 	REG_SEQ0(LANE_REG(0303), 0x2f),
 	REG_SEQ0(LANE_REG(0403), 0x2f),
 	REG_SEQ0(LANE_REG(0503), 0x2f),
@@ -687,6 +683,11 @@ static const struct reg_sequence rk_hdtpx_tmds_lane_init_seq[] = {
 	REG_SEQ0(LANE_REG(0406), 0x1c),
 	REG_SEQ0(LANE_REG(0506), 0x1c),
 	REG_SEQ0(LANE_REG(0606), 0x1c),
+	/* Keep Inter-Pair Skew in the limits */
+	REG_SEQ0(LANE_REG(031e), 0x02),
+	REG_SEQ0(LANE_REG(041e), 0x02),
+	REG_SEQ0(LANE_REG(051e), 0x02),
+	REG_SEQ0(LANE_REG(061e), 0x0a),
 };
 
 static struct tx_drv_ctrl tx_drv_ctrl_rbr[4][4] = {

-- 
2.51.0