drm/i915/skl: Add support for edp1.4 low vswing

Based upon vbt's vswing preemph settings value select the appropriate
translations for edp.

v2: Incorporating bspec changes for vswing and preemph levels, adding edp
translation table. Removed HSW from selection 9 which is specific to skl and
correcting the returning of level2 from max pre emph (Damien)

v3: Rebasing on top of renaming patches. Adding level(3,0) since level(2,2) as
mentioned in bspec is invalid as per edp spec. Also changed the determining of
size of the table selected (Satheesh).

v4: Adding level 3 in max voltage selection if low vswing is selected (Satheesh)

v5: Add a comment stating that skl_ddi_translations_edp is for eDP 1.4
    low vswing panels.

v6: Updating recommended DDI translation table for edp 1.4

Reviewed-by: Satheeshakrishna M <satheeshakrishna.m@intel.com> (v4)
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com> (v6)
Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 40 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index f14e8a2a022d..985d531aaf9e 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -139,6 +139,21 @@ static const struct ddi_buf_trans skl_ddi_translations_dp[] = {
         { 0x00004014, 0x00000087 },
 };
 
+/* eDP 1.4 low vswing translation parameters */
+static const struct ddi_buf_trans skl_ddi_translations_edp[] = {
+        { 0x00000018, 0x000000a8 },
+        { 0x00002016, 0x000000ab },
+        { 0x00006012, 0x000000a2 },
+        { 0x00008010, 0x00000088 },
+        { 0x00000018, 0x000000ab },
+        { 0x00004014, 0x000000a2 },
+        { 0x00006012, 0x000000a6 },
+        { 0x00000018, 0x000000a2 },
+        { 0x00005013, 0x0000009c },
+        { 0x00000018, 0x00000088 },
+};
+
+
 static const struct ddi_buf_trans skl_ddi_translations_hdmi[] = {
                                         /* Idx  NT mV   T mV    db  */
         { 0x00000018, 0x000000a0 },     /* 0:   400     400     0   */
@@ -187,7 +202,8 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
         u32 reg;
-        int i, n_hdmi_entries, hdmi_800mV_0dB;
+        int i, n_hdmi_entries, n_dp_entries, n_edp_entries, hdmi_800mV_0dB,
+            size;
         int hdmi_level = dev_priv->vbt.ddi_port_info[port].hdmi_level_shift;
         const struct ddi_buf_trans *ddi_translations_fdi;
         const struct ddi_buf_trans *ddi_translations_dp;
@@ -198,7 +214,15 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
         if (IS_SKYLAKE(dev)) {
                 ddi_translations_fdi = NULL;
                 ddi_translations_dp = skl_ddi_translations_dp;
-                ddi_translations_edp = skl_ddi_translations_dp;
+                n_dp_entries = ARRAY_SIZE(skl_ddi_translations_dp);
+                if (dev_priv->vbt.edp_low_vswing) {
+                        ddi_translations_edp = skl_ddi_translations_edp;
+                        n_edp_entries = ARRAY_SIZE(skl_ddi_translations_edp);
+                } else {
+                        ddi_translations_edp = skl_ddi_translations_dp;
+                        n_edp_entries = ARRAY_SIZE(skl_ddi_translations_dp);
+                }
+
                 ddi_translations_hdmi = skl_ddi_translations_hdmi;
                 n_hdmi_entries = ARRAY_SIZE(skl_ddi_translations_hdmi);
                 hdmi_800mV_0dB = 7;
@@ -207,6 +231,8 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
                 ddi_translations_dp = bdw_ddi_translations_dp;
                 ddi_translations_edp = bdw_ddi_translations_edp;
                 ddi_translations_hdmi = bdw_ddi_translations_hdmi;
+                n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
+                n_dp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
                 n_hdmi_entries = ARRAY_SIZE(bdw_ddi_translations_hdmi);
                 hdmi_800mV_0dB = 7;
         } else if (IS_HASWELL(dev)) {
@@ -214,6 +240,7 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
                 ddi_translations_dp = hsw_ddi_translations_dp;
                 ddi_translations_edp = hsw_ddi_translations_dp;
                 ddi_translations_hdmi = hsw_ddi_translations_hdmi;
+                n_dp_entries = n_edp_entries = ARRAY_SIZE(hsw_ddi_translations_dp);
                 n_hdmi_entries = ARRAY_SIZE(hsw_ddi_translations_hdmi);
                 hdmi_800mV_0dB = 6;
         } else {
@@ -222,6 +249,8 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
                 ddi_translations_fdi = bdw_ddi_translations_fdi;
                 ddi_translations_dp = bdw_ddi_translations_dp;
                 ddi_translations_hdmi = bdw_ddi_translations_hdmi;
+                n_edp_entries = ARRAY_SIZE(bdw_ddi_translations_edp);
+                n_dp_entries = ARRAY_SIZE(bdw_ddi_translations_dp);
                 n_hdmi_entries = ARRAY_SIZE(bdw_ddi_translations_hdmi);
                 hdmi_800mV_0dB = 7;
         }
@@ -229,29 +258,34 @@ static void intel_prepare_ddi_buffers(struct drm_device *dev, enum port port)
         switch (port) {
         case PORT_A:
                 ddi_translations = ddi_translations_edp;
+                size = n_edp_entries;
                 break;
         case PORT_B:
         case PORT_C:
                 ddi_translations = ddi_translations_dp;
+                size = n_dp_entries;
                 break;
         case PORT_D:
-                if (intel_dp_is_edp(dev, PORT_D))
+                if (intel_dp_is_edp(dev, PORT_D)) {
                         ddi_translations = ddi_translations_edp;
-                else
+                        size = n_edp_entries;
+                } else {
                         ddi_translations = ddi_translations_dp;
+                        size = n_dp_entries;
+                }
                 break;
         case PORT_E:
                 if (ddi_translations_fdi)
                         ddi_translations = ddi_translations_fdi;
                 else
                         ddi_translations = ddi_translations_dp;
+                size = n_dp_entries;
                 break;
         default:
                 BUG();
         }
 
-        for (i = 0, reg = DDI_BUF_TRANS(port);
-             i < ARRAY_SIZE(hsw_ddi_translations_fdi); i++) {
+        for (i = 0, reg = DDI_BUF_TRANS(port); i < size; i++) {
                 I915_WRITE(reg, ddi_translations[i].trans1);
                 reg += 4;
                 I915_WRITE(reg, ddi_translations[i].trans2);