drm/i915/bxt: Set oscaledcompmethod to enable scale value

Bspec update tells that we have to enable oscaledcompmethod instead of
ouniqetrangenmethod for enabling scale value during swing programming.

v2: Adding back 'don't care' values to bxt_ddi_translations_dp and add
error message if ouniquetrangemethod was set (Imre)

Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>(v1)
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -1395,7 +1395,8 @@ enum skl_disp_power_wells {
 #define BXT_PORT_TX_DW3_LN0(port)	_PORT3(port, _PORT_TX_DW3_LN0_A,  \
 						     _PORT_TX_DW3_LN0_B,  \
 						     _PORT_TX_DW3_LN0_C)
-#define   UNIQE_TRANGE_EN_METHOD	(1 << 27)
+#define   SCALE_DCOMP_METHOD		(1 << 26)
+#define   UNIQUE_TRANGE_EN_METHOD	(1 << 27)
 
 #define _PORT_TX_DW4_LN0_A		0x162510
 #define _PORT_TX_DW4_LN0_B		0x6C510

drivers/gpu/drm/i915/intel_ddi.c

@@ -2165,9 +2165,13 @@ static void bxt_ddi_vswing_sequence(struct drm_device *dev, u32 level,
 	I915_WRITE(BXT_PORT_TX_DW2_GRP(port), val);
 
 	val = I915_READ(BXT_PORT_TX_DW3_LN0(port));
-	val &= ~UNIQE_TRANGE_EN_METHOD;
+	val &= ~SCALE_DCOMP_METHOD;
 	if (ddi_translations[level].enable)
-		val |= UNIQE_TRANGE_EN_METHOD;
+		val |= SCALE_DCOMP_METHOD;
+
+	if ((val & UNIQUE_TRANGE_EN_METHOD) && !(val & SCALE_DCOMP_METHOD))
+		DRM_ERROR("Disabled scaling while ouniqetrangenmethod was set");
+
 	I915_WRITE(BXT_PORT_TX_DW3_GRP(port), val);
 
 	val = I915_READ(BXT_PORT_TX_DW4_LN0(port));