[Intel-gfx] [PATCH 34/41] drm/i915: perform Haswell DDI link training in FDI mode

[Eugeni Dodonov]

This patch attempts at following the modeset sequence closely, retrying
with different voltages if the DP_TP_STATUS reports a failed training.

For training, we add a table of recommended settings for FDI, HDMI and DP
connections. For FDI and DP modes, we also add the HDMI buffer
translation as the last item. Those are ignored in such modes, so there is
no harm in having them set.

Initially, we use DDI E for FDI connectivity.  This is the suggested
configuration, and this seems to be what should work the best with FDI.

Note that we leave the DDI Function for corresponding pipe active when we
are done with the training. This ensures that we only need to enable pipe
afterwards to get a working modesetting, in a similar fashion as on
pre-HSW hardware. The modeset disabling sequence mentions a correct order
of disabling things, but this is out of scope of this patch and is being
done separately, for clearer distinction of what happens when.

v2: improve comments a bit, use PORT enums instead of hardcoded PORT_E
registers, split DDI buffers programming into a separate patch.

v1 Reviewed-by: Rodrigo Vivi <rodrigo.vivi at gmail.com>
Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |  118 ++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 1fdcd56..09c18f8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2808,6 +2808,113 @@ static void intel_hsw_prepare_ddi_buffers(struct drm_device *dev)
 	hsw_prepare_ddi_buffers(dev, PORT_E, true);
 }
 
+static const long hsw_ddi_buf_ctl_values[] = {
+	DDI_BUF_EMP_400MV_0DB_HSW,
+	DDI_BUF_EMP_400MV_3_5DB_HSW,
+	DDI_BUF_EMP_400MV_6DB_HSW,
+	DDI_BUF_EMP_400MV_9_5DB_HSW,
+	DDI_BUF_EMP_600MV_0DB_HSW,
+	DDI_BUF_EMP_600MV_3_5DB_HSW,
+	DDI_BUF_EMP_600MV_6DB_HSW,
+	DDI_BUF_EMP_800MV_0DB_HSW,
+	DDI_BUF_EMP_800MV_3_5DB_HSW
+};
+
+
+/* Link training for HSW parts */
+static void hsw_fdi_link_train(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
+	int pipe = intel_crtc->pipe;
+	u32 reg, temp, i;
+
+	/* Configure CPU PLL, wait for warmup */
+	I915_WRITE(SPLL_CTL,
+			SPLL_PLL_ENABLE |
+			SPLL_PLL_FREQ_1350MHz |
+			SPLL_PLL_SCC);
+
+	/* Use SPLL to drive the output when in FDI mode */
+	I915_WRITE(PORT_CLK_SEL(PORT_E),
+			PORT_CLK_SEL_SPLL);
+	I915_WRITE(PIPE_CLK_SEL(pipe),
+			PIPE_CLK_SEL_PORT(PORT_E));
+
+	udelay(20);
+
+	/* Start the training iterating through available voltages and emphasis */
+	for (i=0; i < ARRAY_SIZE(hsw_ddi_buf_ctl_values); i++) {
+		/* Configure DP_TP_CTL with auto-training */
+		I915_WRITE(DP_TP_CTL(PORT_E),
+					DP_TP_CTL_FDI_AUTOTRAIN |
+					DP_TP_CTL_ENHANCED_FRAME_ENABLE |
+					DP_TP_CTL_LINK_TRAIN_PAT1 |
+					DP_TP_CTL_ENABLE);
+
+		/* Configure and enable DDI_BUF_CTL for DDI E with next voltage */
+		temp = I915_READ(DDI_BUF_CTL(PORT_E));
+		temp = (temp & ~DDI_BUF_EMP_MASK);
+		I915_WRITE(DDI_BUF_CTL(PORT_E),
+				temp |
+				DDI_BUF_CTL_ENABLE |
+				DDI_PORT_WIDTH_X2 |
+				hsw_ddi_buf_ctl_values[i]);
+
+		udelay(600);
+
+		/* Enable CPU FDI Receiver with auto-training */
+		reg = FDI_RX_CTL(pipe);
+		I915_WRITE(reg,
+				I915_READ(reg) |
+					FDI_LINK_TRAIN_AUTO |
+					FDI_RX_ENABLE |
+					FDI_LINK_TRAIN_PATTERN_1_CPT |
+					FDI_RX_ENHANCE_FRAME_ENABLE |
+					LPT_FDI_PORT_WIDTH_2X |
+					FDI_RX_PLL_ENABLE);
+		POSTING_READ(reg);
+		udelay(100);
+
+		temp = I915_READ(DP_TP_STATUS(PORT_E));
+		if (temp & DP_TP_STATUS_AUTOTRAIN_DONE) {
+			DRM_INFO("BUF_CTL training done on %d step\n", i);
+
+			/* Enable normal pixel sending for FDI */
+			I915_WRITE(DP_TP_CTL(PORT_E),
+						DP_TP_CTL_FDI_AUTOTRAIN |
+						DP_TP_CTL_LINK_TRAIN_NORMAL |
+						DP_TP_CTL_ENHANCED_FRAME_ENABLE |
+						DP_TP_CTL_ENABLE);
+
+			/* Enable PIPE_DDI_FUNC_CTL for the pipe to work in FDI mode */
+			temp = I915_READ(DDI_FUNC_CTL(pipe));
+			temp &= ~PIPE_DDI_PORT_MASK;
+			temp |= PIPE_DDI_SELECT_PORT(PORT_E) |
+					PIPE_DDI_MODE_SELECT_FDI |
+					PIPE_DDI_FUNC_ENABLE |
+					PIPE_DDI_PORT_WIDTH_X2;
+			I915_WRITE(DDI_FUNC_CTL(pipe),
+					temp);
+			break;
+		} else {
+			DRM_ERROR("Error training BUF_CTL %d\n", i);
+
+			/* Disable DP_TP_CTL and FDI_RX_CTL) and retry */
+			I915_WRITE(DP_TP_CTL(PORT_E),
+					I915_READ(DP_TP_CTL(PORT_E)) &
+						~DP_TP_CTL_ENABLE);
+			I915_WRITE(FDI_RX_CTL(pipe),
+					I915_READ(FDI_RX_CTL(pipe)) &
+						~FDI_RX_PLL_ENABLE);
+			continue;
+		}
+	}
+
+	DRM_DEBUG_KMS("FDI train done.\n");
+}
+
 /* Manual link training for Ivy Bridge A0 parts */
 static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
 {
@@ -9086,6 +9193,17 @@ static void intel_init_display(struct drm_device *dev)
 			}
 			dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
 			dev_priv->display.write_eld = ironlake_write_eld;
+		} else if (IS_HASWELL(dev)) {
+			dev_priv->display.fdi_link_train = hsw_fdi_link_train;
+			if (SNB_READ_WM0_LATENCY()) {
+				dev_priv->display.update_wm = sandybridge_update_wm;
+			} else {
+				DRM_DEBUG_KMS("Failed to read display plane latency. "
+					      "Disable CxSR\n");
+				dev_priv->display.update_wm = NULL;
+			}
+			dev_priv->display.init_clock_gating = ivybridge_init_clock_gating;
+			dev_priv->display.write_eld = ironlake_write_eld;
 		} else
 			dev_priv->display.update_wm = NULL;
 	} else if (IS_PINEVIEW(dev)) {
-- 
1.7.9.5