drm/i915: hsw backlight registers need transcoder instead of pipe

v2: Make TRANSCODER_EDP handling more explicit. (Imre)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_reg.h

@@ -2087,6 +2087,10 @@
 #define   BLM_PIPE_A			(0 << 29)
 #define   BLM_PIPE_B			(1 << 29)
 #define   BLM_PIPE_C			(2 << 29) /* ivb + */
+#define   BLM_TRANSCODER_A		BLM_PIPE_A /* hsw */
+#define   BLM_TRANSCODER_B		BLM_PIPE_B
+#define   BLM_TRANSCODER_C		BLM_PIPE_C
+#define   BLM_TRANSCODER_EDP		(3 << 29)
 #define   BLM_PIPE(pipe)		((pipe) << 29)
 #define   BLM_POLARITY_I965		(1 << 28) /* gen4 only */
 #define   BLM_PHASE_IN_INTERUPT_STATUS	(1 << 26)

drivers/gpu/drm/i915/intel_panel.c

@@ -344,6 +344,8 @@ void intel_panel_enable_backlight(struct drm_device *dev,
 				  enum pipe pipe)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	enum transcoder cpu_transcoder =
+		intel_pipe_to_cpu_transcoder(dev_priv, pipe);
 	unsigned long flags;
 
 	spin_lock_irqsave(&dev_priv->backlight.lock, flags);
@@ -374,7 +376,10 @@ void intel_panel_enable_backlight(struct drm_device *dev,
 		else
 			tmp &= ~BLM_PIPE_SELECT;
 
-		tmp |= BLM_PIPE(pipe);
+		if (cpu_transcoder == TRANSCODER_EDP)
+			tmp |= BLM_TRANSCODER_EDP;
+		else
+			tmp |= BLM_PIPE(cpu_transcoder);
 		tmp &= ~BLM_PWM_ENABLE;
 
 		I915_WRITE(reg, tmp);