drm/i915: make IVB FDI training match spec v3

The existing code was trying different vswing and preemphasis settings
in the wrong place, and wasn't trying them enough.  So add a loop to
walk through them, properly disabling FDI TX and RX in between if a
failure is detected.

v2: remove unneeded reg writes, add delays around bit lock checks (Jesse)
v3: fix TX and RX disable per spec (Paulo)
    fix delays per spec (Paulo)
    make RX symbol lock check match TX bit lock check (Paulo)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=51983
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 72 insertions, 70 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index e600e1cfb6ea..7a40427823c7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2597,7 +2597,7 @@ static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
         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;
+        u32 reg, temp, i, j;
 
         /* Train 1: umask FDI RX Interrupt symbol_lock and bit_lock bit
            for train result */
@@ -2613,97 +2613,99 @@ static void ivb_manual_fdi_link_train(struct drm_crtc *crtc)
         DRM_DEBUG_KMS("FDI_RX_IIR before link train 0x%x\n",
                       I915_READ(FDI_RX_IIR(pipe)));
 
-        /* enable CPU FDI TX and PCH FDI RX */
-        reg = FDI_TX_CTL(pipe);
-        temp = I915_READ(reg);
-        temp &= ~FDI_DP_PORT_WIDTH_MASK;
-        temp |= FDI_DP_PORT_WIDTH(intel_crtc->config.fdi_lanes);
-        temp &= ~(FDI_LINK_TRAIN_AUTO | FDI_LINK_TRAIN_NONE_IVB);
-        temp |= FDI_LINK_TRAIN_PATTERN_1_IVB;
-        temp &= ~FDI_LINK_TRAIN_VOL_EMP_MASK;
-        temp |= FDI_LINK_TRAIN_400MV_0DB_SNB_B;
-        temp |= FDI_COMPOSITE_SYNC;
-        I915_WRITE(reg, temp | FDI_TX_ENABLE);
-
-        I915_WRITE(FDI_RX_MISC(pipe),
-                   FDI_RX_TP1_TO_TP2_48 | FDI_RX_FDI_DELAY_90);
-
-        reg = FDI_RX_CTL(pipe);
-        temp = I915_READ(reg);
-        temp &= ~FDI_LINK_TRAIN_AUTO;
-        temp &= ~FDI_LINK_TRAIN_PATTERN_MASK_CPT;
-        temp |= FDI_LINK_TRAIN_PATTERN_1_CPT;
-        temp |= FDI_COMPOSITE_SYNC;
-        I915_WRITE(reg, temp | FDI_RX_ENABLE);
+        /* Try each vswing and preemphasis setting twice before moving on */
+        for (j = 0; j < ARRAY_SIZE(snb_b_fdi_train_param) * 2; j++) {
+                /* disable first in case we need to retry */
+                reg = FDI_TX_CTL(pipe);
+                temp = I915_READ(reg);
+                temp &= ~(FDI_LINK_TRAIN_AUTO | FDI_LINK_TRAIN_NONE_IVB);
+                temp &= ~FDI_TX_ENABLE;
+                I915_WRITE(reg, temp);
 
-        POSTING_READ(reg);
-        udelay(150);
+                reg = FDI_RX_CTL(pipe);
+                temp = I915_READ(reg);
+                temp &= ~FDI_LINK_TRAIN_AUTO;
+                temp &= ~FDI_LINK_TRAIN_PATTERN_MASK_CPT;
+                temp &= ~FDI_RX_ENABLE;
+                I915_WRITE(reg, temp);
 
-        for (i = 0; i < 4; i++) {
+                /* enable CPU FDI TX and PCH FDI RX */
                 reg = FDI_TX_CTL(pipe);
                 temp = I915_READ(reg);
+                temp &= ~FDI_DP_PORT_WIDTH_MASK;
+                temp |= FDI_DP_PORT_WIDTH(intel_crtc->config.fdi_lanes);
+                temp |= FDI_LINK_TRAIN_PATTERN_1_IVB;
                 temp &= ~FDI_LINK_TRAIN_VOL_EMP_MASK;
-                temp |= snb_b_fdi_train_param[i];
-                I915_WRITE(reg, temp);
+                temp |= snb_b_fdi_train_param[j/2];
+                temp |= FDI_COMPOSITE_SYNC;
+                I915_WRITE(reg, temp | FDI_TX_ENABLE);
 
-                POSTING_READ(reg);
-                udelay(500);
+                I915_WRITE(FDI_RX_MISC(pipe),
+                           FDI_RX_TP1_TO_TP2_48 | FDI_RX_FDI_DELAY_90);
 
-                reg = FDI_RX_IIR(pipe);
+                reg = FDI_RX_CTL(pipe);
                 temp = I915_READ(reg);
-                DRM_DEBUG_KMS("FDI_RX_IIR 0x%x\n", temp);
-
-                if (temp & FDI_RX_BIT_LOCK ||
-                    (I915_READ(reg) & FDI_RX_BIT_LOCK)) {
-                        I915_WRITE(reg, temp | FDI_RX_BIT_LOCK);
-                        DRM_DEBUG_KMS("FDI train 1 done, level %i.\n", i);
-                        break;
-                }
-        }
-        if (i == 4)
-                DRM_ERROR("FDI train 1 fail!\n");
+                temp |= FDI_LINK_TRAIN_PATTERN_1_CPT;
+                temp |= FDI_COMPOSITE_SYNC;
+                I915_WRITE(reg, temp | FDI_RX_ENABLE);
 
-        /* Train 2 */
-        reg = FDI_TX_CTL(pipe);
-        temp = I915_READ(reg);
-        temp &= ~FDI_LINK_TRAIN_NONE_IVB;
-        temp |= FDI_LINK_TRAIN_PATTERN_2_IVB;
-        temp &= ~FDI_LINK_TRAIN_VOL_EMP_MASK;
-        temp |= FDI_LINK_TRAIN_400MV_0DB_SNB_B;
-        I915_WRITE(reg, temp);
+                POSTING_READ(reg);
+                udelay(1); /* should be 0.5us */
 
-        reg = FDI_RX_CTL(pipe);
-        temp = I915_READ(reg);
-        temp &= ~FDI_LINK_TRAIN_PATTERN_MASK_CPT;
-        temp |= FDI_LINK_TRAIN_PATTERN_2_CPT;
-        I915_WRITE(reg, temp);
+                for (i = 0; i < 4; i++) {
+                        reg = FDI_RX_IIR(pipe);
+                        temp = I915_READ(reg);
+                        DRM_DEBUG_KMS("FDI_RX_IIR 0x%x\n", temp);
 
-        POSTING_READ(reg);
-        udelay(150);
+                        if (temp & FDI_RX_BIT_LOCK ||
+                            (I915_READ(reg) & FDI_RX_BIT_LOCK)) {
+                                I915_WRITE(reg, temp | FDI_RX_BIT_LOCK);
+                                DRM_DEBUG_KMS("FDI train 1 done, level %i.\n",
+                                              i);
+                                break;
+                        }
+                        udelay(1); /* should be 0.5us */
+                }
+                if (i == 4) {
+                        DRM_DEBUG_KMS("FDI train 1 fail on vswing %d\n", j / 2);
+                        continue;
+                }
 
-        for (i = 0; i < 4; i++) {
+                /* Train 2 */
                 reg = FDI_TX_CTL(pipe);
                 temp = I915_READ(reg);
-                temp &= ~FDI_LINK_TRAIN_VOL_EMP_MASK;
-                temp |= snb_b_fdi_train_param[i];
+                temp &= ~FDI_LINK_TRAIN_NONE_IVB;
+                temp |= FDI_LINK_TRAIN_PATTERN_2_IVB;
+                I915_WRITE(reg, temp);
+
+                reg = FDI_RX_CTL(pipe);
+                temp = I915_READ(reg);
+                temp &= ~FDI_LINK_TRAIN_PATTERN_MASK_CPT;
+                temp |= FDI_LINK_TRAIN_PATTERN_2_CPT;
                 I915_WRITE(reg, temp);
 
                 POSTING_READ(reg);
-                udelay(500);
+                udelay(2); /* should be 1.5us */
 
-                reg = FDI_RX_IIR(pipe);
-                temp = I915_READ(reg);
-                DRM_DEBUG_KMS("FDI_RX_IIR 0x%x\n", temp);
+                for (i = 0; i < 4; i++) {
+                        reg = FDI_RX_IIR(pipe);
+                        temp = I915_READ(reg);
+                        DRM_DEBUG_KMS("FDI_RX_IIR 0x%x\n", temp);
 
-                if (temp & FDI_RX_SYMBOL_LOCK) {
-                        I915_WRITE(reg, temp | FDI_RX_SYMBOL_LOCK);
-                        DRM_DEBUG_KMS("FDI train 2 done, level %i.\n", i);
-                        break;
+                        if (temp & FDI_RX_SYMBOL_LOCK ||
+                            (I915_READ(reg) & FDI_RX_SYMBOL_LOCK)) {
+                                I915_WRITE(reg, temp | FDI_RX_SYMBOL_LOCK);
+                                DRM_DEBUG_KMS("FDI train 2 done, level %i.\n",
+                                              i);
+                                goto train_done;
+                        }
+                        udelay(2); /* should be 1.5us */
                 }
+                if (i == 4)
+                        DRM_DEBUG_KMS("FDI train 2 fail on vswing %d\n", j / 2);
         }
-        if (i == 4)
-                DRM_ERROR("FDI train 2 fail!\n");
 
+train_done:
         DRM_DEBUG_KMS("FDI train done.\n");
 }