drm/i915: Refactor translate_signal_level()

Convert the big switch statement in translate_signal_level() into a neat
table. The table also serves as documentation for the translation
tables. We'll also have other uses for this table later on.

v2: Remove superfluous space (David)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170223173507.17600-2-ville.syrjala@linux.intel.com
Reviewed-by: David Weinehall <david.weinehall@linux.intel.com>

diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 5e4b0172810dd6c853884548943106740af5547b..7694f4fcce4e524b813514034ea87cece44256f3 100644 (file)
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -34,6 +34,19 @@ struct ddi_buf_trans {
        u8 i_boost;     /* SKL: I_boost; valid: 0x0, 0x1, 0x3, 0x7 */
 };
 
+static const u8 index_to_dp_signal_levels[] = {
+       [0] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_0,
+       [1] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_1,
+       [2] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_2,
+       [3] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_3,
+       [4] = DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_0,
+       [5] = DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_1,
+       [6] = DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_2,
+       [7] = DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_0,
+       [8] = DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_1,
+       [9] = DP_TRAIN_VOLTAGE_SWING_LEVEL_3 | DP_TRAIN_PRE_EMPH_LEVEL_0,
+};
+
 /* HDMI/DVI modes ignore everything but the last 2 items. So we share
  * them for both DP and FDI transports, allowing those ports to
  * automatically adapt to HDMI connections as well
@@ -1604,48 +1617,17 @@ static void bxt_ddi_vswing_sequence(struct drm_i915_private *dev_priv,
 
 static uint32_t translate_signal_level(int signal_levels)
 {
-       uint32_t level;
-
-       switch (signal_levels) {
-       default:
-               DRM_DEBUG_KMS("Unsupported voltage swing/pre-emphasis level: 0x%x\n",
-                             signal_levels);
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_0:
-               level = 0;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_1:
-               level = 1;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_2:
-               level = 2;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_0 | DP_TRAIN_PRE_EMPH_LEVEL_3:
-               level = 3;
-               break;
-
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_0:
-               level = 4;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_1:
-               level = 5;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_1 | DP_TRAIN_PRE_EMPH_LEVEL_2:
-               level = 6;
-               break;
-
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_0:
-               level = 7;
-               break;
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_2 | DP_TRAIN_PRE_EMPH_LEVEL_1:
-               level = 8;
-               break;
+       int i;
 
-       case DP_TRAIN_VOLTAGE_SWING_LEVEL_3 | DP_TRAIN_PRE_EMPH_LEVEL_0:
-               level = 9;
-               break;
+       for (i = 0; i < ARRAY_SIZE(index_to_dp_signal_levels); i++) {
+               if (index_to_dp_signal_levels[i] == signal_levels)
+                       return i;
        }
 
-       return level;
+       WARN(1, "Unsupported voltage swing/pre-emphasis level: 0x%x\n",
+            signal_levels);
+
+       return 0;
 }
 
 uint32_t ddi_signal_levels(struct intel_dp *intel_dp)