drm/i915: Gather the HDMI level shifter logic into one place

The knowledge about the HDMI/DVI DDI translation table was scattered
around.
  - info->hdmi_level_shift was initialized with 6, the index of the 800
    mV, 0dB translation
  - A check on the VBT value was done to ensure it wasn't overflowing
    the translation table (< 0xC)
  - The actual programming was done in intel_ddi.c

As we need to change that knowledge for Broadwell, let's gather
everything into one place.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ce30bb3..0d7e55f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1232,6 +1232,12 @@ enum modeset_restore {
 };
 
 struct ddi_vbt_port_info {
+       /*
+        * This is an index in the HDMI/DVI DDI buffer translation table.
+        * The special value HDMI_LEVEL_SHIFT_UNKNOWN means the VBT didn't
+        * populate this field.
+        */
+#define HDMI_LEVEL_SHIFT_UNKNOWN       0xff
        uint8_t hdmi_level_shift;
 
        uint8_t supports_dvi:1;

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index a669550..031c565 100644 (file)
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -976,12 +976,10 @@ static void parse_ddi_port(struct drm_i915_private *dev_priv, enum port port,
        if (bdb->version >= 158) {
                /* The VBT HDMI level shift values match the table we have. */
                hdmi_level_shift = child->raw[7] & 0xF;
-               if (hdmi_level_shift < 0xC) {
-                       DRM_DEBUG_KMS("VBT HDMI level shift for port %c: %d\n",
-                                     port_name(port),
-                                     hdmi_level_shift);
-                       info->hdmi_level_shift = hdmi_level_shift;
-               }
+               DRM_DEBUG_KMS("VBT HDMI level shift for port %c: %d\n",
+                             port_name(port),
+                             hdmi_level_shift);
+               info->hdmi_level_shift = hdmi_level_shift;
        }
 }
 
@@ -1114,8 +1112,7 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
                struct ddi_vbt_port_info *info =
                        &dev_priv->vbt.ddi_port_info[port];
 
-               /* Recommended BSpec default: 800mV 0dB. */
-               info->hdmi_level_shift = 6;
+               info->hdmi_level_shift = HDMI_LEVEL_SHIFT_UNKNOWN;
 
                info->supports_dvi = (port != PORT_A && port != PORT_E);
                info->supports_hdmi = info->supports_dvi;

diff --cc drivers/gpu/drm/i915/intel_ddi.c
Simple merge