Linux-PHY Archive on lore.kernel.org

* [PATCH 2/2] phy: rockchip: samsung-hdptx: Add support for FRL TxFFE level control
From: Cristian Ciocaltea @ 2026-03-28 13:54 UTC (permalink / raw)
  To: Vinod Koul, Neil Armstrong, Heiko Stuebner
  Cc: kernel, linux-phy, linux-kernel, linux-arm-kernel, linux-rockchip
In-Reply-To: <20260328-hdptx-ffe-v1-0-53ebd5dea20a@collabora.com>

During HDMI 2.1 FRL link training, the source may need to incrementally
raise the TxFFE level in response to persistent link failures reported
by the sink during LTS3.  The phy_configure_opts_hdmi struct now carries
ffe_level and set_ffe_level fields to convey such an update
independently of a full rate reconfiguration.

Wire up the optional TxFFE control in the Samsung HDPTX PHY driver.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c | 74 +++++++++++++++++++++--
 1 file changed, 69 insertions(+), 5 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
index 3bde7fbb34b1..c4669853ad0e 100644
--- a/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
+++ b/drivers/phy/rockchip/phy-rockchip-samsung-hdptx.c
@@ -333,6 +333,7 @@
 #define FRL_3G3L_RATE			900000000
 #define FRL_6G3L_RATE			1800000000
 #define FRL_8G4L_RATE			3200000000
+#define FRL_FFE_MAX_LEVEL		3
 
 enum dp_link_rate {
 	DP_BW_RBR,
@@ -466,6 +467,16 @@ static const struct ropll_config rk_hdptx_tmds_ropll_cfg[] = {
 	{  25175000ULL,   84,    84,    1,    1,   15,  1,  168,    1,  16,  4,   1,    1, },
 };
 
+static const struct ffe_config {
+	u8 pre_shoot;
+	u8 de_emphasis;
+} rk_hdptx_frl_ffe_cfg[FRL_FFE_MAX_LEVEL + 1] = {
+	{ 0x3, 0x4 },
+	{ 0x3, 0x6 },
+	{ 0x3, 0x8 },
+	{ 0x3, 0x9 },
+};
+
 static const struct reg_sequence rk_hdptx_common_cmn_init_seq[] = {
 	REG_SEQ0(CMN_REG(0009), 0x0c),
 	REG_SEQ0(CMN_REG(000a), 0x83),
@@ -1321,6 +1332,45 @@ static int rk_hdptx_tmds_ropll_mode_config(struct rk_hdptx_phy *hdptx)
 	return rk_hdptx_post_enable_lane(hdptx);
 }
 
+static int rk_hdptx_frl_ffe_config(struct rk_hdptx_phy *hdptx, u8 ffe_level)
+{
+	u8 val;
+
+	if (ffe_level > FRL_FFE_MAX_LEVEL)
+		return -EINVAL;
+
+	val = rk_hdptx_frl_ffe_cfg[ffe_level].pre_shoot;
+
+	regmap_update_bits(hdptx->regmap, LANE_REG(0305),
+			   LN_TX_DRV_PRE_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_PRE_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0405),
+			   LN_TX_DRV_PRE_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_PRE_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0505),
+			   LN_TX_DRV_PRE_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_PRE_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0605),
+			   LN_TX_DRV_PRE_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_PRE_LVL_CTRL_MASK, val));
+
+	val = rk_hdptx_frl_ffe_cfg[ffe_level].de_emphasis;
+
+	regmap_update_bits(hdptx->regmap, LANE_REG(0304),
+			   LN_TX_DRV_POST_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_POST_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0404),
+			   LN_TX_DRV_POST_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_POST_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0504),
+			   LN_TX_DRV_POST_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_POST_LVL_CTRL_MASK, val));
+	regmap_update_bits(hdptx->regmap, LANE_REG(0604),
+			   LN_TX_DRV_POST_LVL_CTRL_MASK,
+			   FIELD_PREP(LN_TX_DRV_POST_LVL_CTRL_MASK, val));
+	return 0;
+}
+
 static void rk_hdptx_dp_reset(struct rk_hdptx_phy *hdptx)
 {
 	reset_control_assert(hdptx->rsts[RST_LANE].rstc);
@@ -1730,6 +1780,13 @@ static int rk_hdptx_phy_verify_hdmi_config(struct rk_hdptx_phy *hdptx,
 		unsigned long long frl_rate = 100000000ULL * hdmi_in->frl.lanes *
 					      hdmi_in->frl.rate_per_lane;
 
+		if (hdmi_in->frl.set_ffe_level) {
+			if (hdmi_in->frl.ffe_level > FRL_FFE_MAX_LEVEL)
+				return -EINVAL;
+
+			return 0;
+		}
+
 		switch (hdmi_in->frl.rate_per_lane) {
 		case 3:
 		case 6:
@@ -2076,11 +2133,18 @@ static int rk_hdptx_phy_configure(struct phy *phy, union phy_configure_opts *opt
 		if (ret) {
 			dev_err(hdptx->dev, "invalid hdmi params for phy configure\n");
 		} else {
-			hdptx->pll_config_dirty = true;
-
-			dev_dbg(hdptx->dev, "%s %s rate=%llu bpc=%u\n", __func__,
-				hdptx->hdmi_cfg.mode ? "FRL" : "TMDS",
-				hdptx->hdmi_cfg.rate, hdptx->hdmi_cfg.bpc);
+			if (hdptx->hdmi_cfg.mode == PHY_HDMI_MODE_FRL &&
+			    opts->hdmi.frl.set_ffe_level) {
+				dev_dbg(hdptx->dev, "%s ffe_level=%u\n", __func__,
+					opts->hdmi.frl.ffe_level);
+				ret = rk_hdptx_frl_ffe_config(hdptx, opts->hdmi.frl.ffe_level);
+			} else {
+				hdptx->pll_config_dirty = true;
+
+				dev_dbg(hdptx->dev, "%s %s rate=%llu bpc=%u\n", __func__,
+					hdptx->hdmi_cfg.mode ? "FRL" : "TMDS",
+					hdptx->hdmi_cfg.rate, hdptx->hdmi_cfg.bpc);
+			}
 		}
 
 		return ret;

-- 
2.52.0


-- 
linux-phy mailing list
linux-phy@lists.infradead.org
https://lists.infradead.org/mailman/listinfo/linux-phy

^ permalink raw reply related