[Intel-gfx] [PATCH 09/20] drm/i915/icl: DSI vswing programming sequence

[Madhav Chauhan]

This patch setup voltage swing before enabling
combo PHY DDI (shared with DSI).
Note that DSI voltage swing programming is for
high speed data buffers. HW automatically handles
the voltage swing for the low power data buffers.

Signed-off-by: Madhav Chauhan <madhav.chauhan at intel.com>
---
 drivers/gpu/drm/i915/intel_dsi_new.c | 114 +++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_dsi_new.c b/drivers/gpu/drm/i915/intel_dsi_new.c
index cf52160..252af06 100644
--- a/drivers/gpu/drm/i915/intel_dsi_new.c
+++ b/drivers/gpu/drm/i915/intel_dsi_new.c
@@ -28,6 +28,65 @@
 
 #include "intel_dsi.h"
 
+static void dsi_program_swing_and_deemphasis(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	enum port port;
+	u32 tmp;
+	int lane;
+
+	for_each_dsi_port(port, intel_dsi->ports) {
+
+		/* Bspec: set scaling mode to 0x6 */
+		tmp = I915_READ(ICL_PORT_TX_DW5_LN0(port));
+		tmp |= SCALING_MODE_SEL(6);
+		I915_WRITE(ICL_PORT_TX_DW5_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW5_AUX(port));
+		tmp |= SCALING_MODE_SEL(6);
+		I915_WRITE(ICL_PORT_TX_DW5_AUX(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW5_LN0(port));
+		tmp |= TAP2_DISABLE | TAP3_DISABLE;
+		I915_WRITE(ICL_PORT_TX_DW5_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW5_AUX(port));
+		tmp |= TAP2_DISABLE | TAP3_DISABLE;
+		I915_WRITE(ICL_PORT_TX_DW5_AUX(port), tmp);
+
+		/*
+		 * swing and scaling values are taken from DSI
+		 * table under vswing programming sequence for
+		 * combo phy ddi in BSPEC.
+		 * program swing values
+		 */
+		tmp = I915_READ(ICL_PORT_TX_DW2_LN0(port));
+		tmp |= SWING_SEL_UPPER(0x2);
+		tmp |= SWING_SEL_LOWER(0x2);
+		tmp |= RCOMP_SCALAR(0x98);
+		I915_WRITE(ICL_PORT_TX_DW2_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW2_AUX(port));
+		tmp |= SWING_SEL_UPPER(0x2);
+		tmp |= SWING_SEL_LOWER(0x2);
+		tmp |= RCOMP_SCALAR(0x98);
+		I915_WRITE(ICL_PORT_TX_DW2_AUX(port), tmp);
+
+		/* program scaling values */
+		tmp = I915_READ(ICL_PORT_TX_DW4_AUX(port));
+		tmp |= POST_CURSOR_1(0x0);
+		tmp |= POST_CURSOR_2(0x0);
+		tmp |= CURSOR_COEFF(0x18);
+		I915_WRITE(ICL_PORT_TX_DW4_AUX(port), tmp);
+
+		for (lane = 0; lane <= 3; lane++) {
+			/* Bspec: must not use GRP register for write */
+			tmp = I915_READ(ICL_PORT_TX_DW4_LN(port, lane));
+			tmp |= POST_CURSOR_1(0x0);
+			tmp |= POST_CURSOR_2(0x0);
+			tmp |= CURSOR_COEFF(0x18);
+			I915_WRITE(ICL_PORT_TX_DW4_LN(port, lane), tmp);
+		}
+	}
+}
+
 static void gen11_dsi_program_esc_clk_div(struct intel_encoder *encoder)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
@@ -144,6 +203,58 @@ static void gen11_dsi_config_phy_lanes_sequence(struct intel_encoder *encoder)
 	}
 }
 
+static void gen11_dsi_voltage_swing_program_seq(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+	struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
+	u32 tmp;
+	enum port port;
+
+	/* Step C.1:clear common keeper enable bit */
+	for_each_dsi_port(port, intel_dsi->ports) {
+		tmp = I915_READ(ICL_PORT_PCS_DW1_LN0(port));
+		tmp &= ~COMMON_KEEPER_EN;
+		I915_WRITE(ICL_PORT_PCS_DW1_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_PCS_DW1_AUX(port));
+		tmp &= ~COMMON_KEEPER_EN;
+		I915_WRITE(ICL_PORT_PCS_DW1_AUX(port), tmp);
+	}
+
+	/*
+	 * Step C.3: Set SUS Clock Config bitfield to 11b
+	 * Note: Step C.2 (loadgen select program) is done
+	 * as part of lane phy sequence configuration
+	 */
+	for_each_dsi_port(port, intel_dsi->ports) {
+		tmp = I915_READ(ICL_PORT_CL_DW5(port));
+		tmp |= SUS_CLOCK_CONFIG;
+		I915_WRITE(ICL_PORT_CL_DW5(port), tmp);
+	}
+
+	/* Step C.4: Clear training enable to change swing values */
+	for_each_dsi_port(port, intel_dsi->ports) {
+		tmp = I915_READ(ICL_PORT_TX_DW5_LN0(port));
+		tmp &= ~TX_TRAINING_EN;
+		I915_WRITE(ICL_PORT_TX_DW5_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW5_AUX(port));
+		tmp &= ~TX_TRAINING_EN;
+		I915_WRITE(ICL_PORT_TX_DW5_AUX(port), tmp);
+	}
+
+	/* Step C.5: Program swing and de-emphasis */
+	dsi_program_swing_and_deemphasis(encoder);
+
+	/* Step: C.6: Set training enable to trigger update */
+	for_each_dsi_port(port, intel_dsi->ports) {
+		tmp = I915_READ(ICL_PORT_TX_DW5_LN0(port));
+		tmp |= TX_TRAINING_EN;
+		I915_WRITE(ICL_PORT_TX_DW5_GRP(port), tmp);
+		tmp = I915_READ(ICL_PORT_TX_DW5_AUX(port));
+		tmp |= TX_TRAINING_EN;
+		I915_WRITE(ICL_PORT_TX_DW5_AUX(port), tmp);
+	}
+}
+
 static void gen11_dsi_enable_port_and_phy(struct intel_encoder *encoder)
 {
 	/* step 4a: power up all lanes of the DDI used by DSI */
@@ -151,6 +262,9 @@ static void gen11_dsi_enable_port_and_phy(struct intel_encoder *encoder)
 
 	/* step 4b: configure lane sequencing of the Combo-PHY transmitters */
 	gen11_dsi_config_phy_lanes_sequence(encoder);
+
+	/* step 4c: configure voltage swing and skew */
+	gen11_dsi_voltage_swing_program_seq(encoder);
 }
 
 static void __attribute__((unused)) gen11_dsi_pre_enable(
-- 
2.7.4