drm/i915: add basic MIPI DSI output support

This does not include any panel specific sub-encoders yet.

v2: Fix fixed mode handling (Daniel)

v3: Mostly based on Ville's review comments.
 - Fix MIPI_HS_TX_TIMEOUT.
 - DPI_ENABLE only for video mode.
 - Drop ULPS usage for now, use DEVICE_READY only.
 - Set MIPI_INIT_COUNT based on txclkesc.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/Makefile

@@ -21,6 +21,7 @@ i915-y := i915_drv.o i915_dma.o i915_irq.o \
 	  intel_display.o \
 	  intel_crt.o \
 	  intel_lvds.o \
+	  intel_dsi.o \
 	  intel_dsi_cmd.o \
 	  intel_bios.o \
 	  intel_ddi.o \

drivers/gpu/drm/i915/intel_drv.h

@@ -525,6 +525,7 @@ extern void intel_mark_fb_busy(struct drm_i915_gem_object *obj,
 			       struct intel_ring_buffer *ring);
 extern void intel_mark_idle(struct drm_device *dev);
 extern void intel_lvds_init(struct drm_device *dev);
+extern bool intel_dsi_init(struct drm_device *dev);
 extern bool intel_is_dual_link_lvds(struct drm_device *dev);
 extern void intel_dp_init(struct drm_device *dev, int output_reg,
 			  enum port port);