u32 val = I915_READ(VIDEO_DIP_CTL);
        unsigned i, len = DIP_HEADER_SIZE + frame->len;
 
+       WARN(!(val & VIDEO_DIP_ENABLE), "Writing DIP with CTL reg disabled\n");
+
        val &= ~(VIDEO_DIP_SELECT_MASK | 0xf); /* clear DIP data offset */
        val |= g4x_infoframe_index(frame);
 
        val &= ~g4x_infoframe_enable(frame);
-       val |= VIDEO_DIP_ENABLE;
 
        I915_WRITE(VIDEO_DIP_CTL, val);
 
        unsigned i, len = DIP_HEADER_SIZE + frame->len;
        u32 val = I915_READ(reg);
 
+       WARN(!(val & VIDEO_DIP_ENABLE), "Writing DIP with CTL reg disabled\n");
+
        intel_wait_for_vblank(dev, intel_crtc->pipe);
 
        val &= ~(VIDEO_DIP_SELECT_MASK | 0xf); /* clear DIP data offset */
        val |= g4x_infoframe_index(frame);
 
        val &= ~g4x_infoframe_enable(frame);
-       val |= VIDEO_DIP_ENABLE;
 
        I915_WRITE(reg, val);
 
        unsigned i, len = DIP_HEADER_SIZE + frame->len;
        u32 val = I915_READ(reg);
 
+       WARN(!(val & VIDEO_DIP_ENABLE), "Writing DIP with CTL reg disabled\n");
+
        intel_wait_for_vblank(dev, intel_crtc->pipe);
 
        val &= ~(VIDEO_DIP_SELECT_MASK | 0xf); /* clear DIP data offset */
 
        /* The DIP control register spec says that we need to update the AVI
         * infoframe without clearing its enable bit */
-       if (frame->type == DIP_TYPE_AVI)
-               val |= VIDEO_DIP_ENABLE_AVI;
-       else
+       if (frame->type != DIP_TYPE_AVI)
                val &= ~g4x_infoframe_enable(frame);
 
-       val |= VIDEO_DIP_ENABLE;
-
        I915_WRITE(reg, val);
 
        for (i = 0; i < len; i += 4) {
        unsigned i, len = DIP_HEADER_SIZE + frame->len;
        u32 val = I915_READ(reg);
 
+       WARN(!(val & VIDEO_DIP_ENABLE), "Writing DIP with CTL reg disabled\n");
+
        intel_wait_for_vblank(dev, intel_crtc->pipe);
 
        val &= ~(VIDEO_DIP_SELECT_MASK | 0xf); /* clear DIP data offset */
        val |= g4x_infoframe_index(frame);
 
        val &= ~g4x_infoframe_enable(frame);
-       val |= VIDEO_DIP_ENABLE;
 
        I915_WRITE(reg, val);
 
                return;
        }
 
+       val |= VIDEO_DIP_ENABLE;
+
        I915_WRITE(reg, val);
 
        intel_hdmi_set_avi_infoframe(encoder, adjusted_mode);
                return;
        }
 
+       val |= VIDEO_DIP_ENABLE;
+
        I915_WRITE(reg, val);
 
        intel_hdmi_set_avi_infoframe(encoder, adjusted_mode);
                return;
        }
 
+       /* Set both together, unset both together: see the spec. */
+       val |= VIDEO_DIP_ENABLE | VIDEO_DIP_ENABLE_AVI;
+
+       I915_WRITE(reg, val);
+
        intel_hdmi_set_avi_infoframe(encoder, adjusted_mode);
        intel_hdmi_set_spd_infoframe(encoder);
 }
                return;
        }
 
+       val |= VIDEO_DIP_ENABLE;
+
+       I915_WRITE(reg, val);
+
        intel_hdmi_set_avi_infoframe(encoder, adjusted_mode);
        intel_hdmi_set_spd_infoframe(encoder);
 }