drm/i915: make DBLCLK modes work

They require an AVI InfoFrame with a proper Pixel Repetition field.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=45729
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_drv.h

@@ -234,6 +234,8 @@ struct cxsr_latency {
 #define DIP_TYPE_AVI    0x82
 #define DIP_VERSION_AVI 0x2
 #define DIP_LEN_AVI     13
+#define DIP_AVI_PR_1    0
+#define DIP_AVI_PR_2    1
 
 #define DIP_TYPE_SPD	0x83
 #define DIP_VERSION_SPD	0x1

drivers/gpu/drm/i915/intel_hdmi.c

@@ -220,7 +220,8 @@ static void intel_set_infoframe(struct drm_encoder *encoder,
 	intel_hdmi->write_infoframe(encoder, frame);
 }
 
-static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder)
+static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder,
+					 struct drm_display_mode *adjusted_mode)
 {
 	struct dip_infoframe avi_if = {
 		.type = DIP_TYPE_AVI,
@@ -228,6 +229,9 @@ static void intel_hdmi_set_avi_infoframe(struct drm_encoder *encoder)
 		.len = DIP_LEN_AVI,
 	};
 
+	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
+		avi_if.body.avi.YQ_CN_PR |= DIP_AVI_PR_2;
+
 	intel_set_infoframe(encoder, &avi_if);
 }
 
@@ -290,7 +294,7 @@ static void intel_hdmi_mode_set(struct drm_encoder *encoder,
 	I915_WRITE(intel_hdmi->sdvox_reg, sdvox);
 	POSTING_READ(intel_hdmi->sdvox_reg);
 
-	intel_hdmi_set_avi_infoframe(encoder);
+	intel_hdmi_set_avi_infoframe(encoder, adjusted_mode);
 	intel_hdmi_set_spd_infoframe(encoder);
 }