drm/i915: Constify states passed to enable/disable/etc. encoder hooks

The enable/disable/etc. encoder hooks aren't supposed to alter the
state(s), so pass them as const. Unfortunately C lacks any kind of deep
const thingy, so this can't catch all abuses. But at least it acts as a
hint to the reader telling them not to mess about with the state(s).

v2: Update intel_tv_mode_find() and ironlake_edp_pll_on() as well
v3: Deal with intel_sdvo_connector_state

Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170818134958.15502-9-ville.syrjala@linux.intel.com
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 70e0ff4..a77dd80 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -143,7 +143,7 @@
 /* Note: The caller is required to filter out dpms modes not supported by the
  * platform. */
 static void intel_crt_set_dpms(struct intel_encoder *encoder,
-			       struct intel_crtc_state *crtc_state,
+			       const struct intel_crtc_state *crtc_state,
 			       int mode)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
@@ -194,28 +194,28 @@
 }
 
 static void intel_disable_crt(struct intel_encoder *encoder,
-			      struct intel_crtc_state *old_crtc_state,
-			      struct drm_connector_state *old_conn_state)
+			      const struct intel_crtc_state *old_crtc_state,
+			      const struct drm_connector_state *old_conn_state)
 {
 	intel_crt_set_dpms(encoder, old_crtc_state, DRM_MODE_DPMS_OFF);
 }
 
 static void pch_disable_crt(struct intel_encoder *encoder,
-			    struct intel_crtc_state *old_crtc_state,
-			    struct drm_connector_state *old_conn_state)
+			    const struct intel_crtc_state *old_crtc_state,
+			    const struct drm_connector_state *old_conn_state)
 {
 }
 
 static void pch_post_disable_crt(struct intel_encoder *encoder,
-				 struct intel_crtc_state *old_crtc_state,
-				 struct drm_connector_state *old_conn_state)
+				 const struct intel_crtc_state *old_crtc_state,
+				 const struct drm_connector_state *old_conn_state)
 {
 	intel_disable_crt(encoder, old_crtc_state, old_conn_state);
 }
 
 static void hsw_post_disable_crt(struct intel_encoder *encoder,
-				 struct intel_crtc_state *old_crtc_state,
-				 struct drm_connector_state *old_conn_state)
+				 const struct intel_crtc_state *old_crtc_state,
+				 const struct drm_connector_state *old_conn_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
 
@@ -228,8 +228,8 @@
 }
 
 static void intel_enable_crt(struct intel_encoder *encoder,
-			     struct intel_crtc_state *pipe_config,
-			     struct drm_connector_state *conn_state)
+			     const struct intel_crtc_state *pipe_config,
+			     const struct drm_connector_state *conn_state)
 {
 	intel_crt_set_dpms(encoder, pipe_config, DRM_MODE_DPMS_ON);
 }