drm/i915: extract intel_dp_link_training.h from intel_drv.h

It used to be handy that we only had a couple of headers, but over time
intel_drv.h has become unwieldy. Extract declarations to a separate
header file corresponding to the implementation module, clarifying the
modularity of the driver.

Ensure the new header is self-contained, and do so with minimal further
includes, using forward declarations as needed. Include the new header
only where needed, and sort the modified include directives while at it
and as needed.

No functional changes.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/eb23be64d04957b2cf82b79fd69cc57ed84043a4.1556540889.git.jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile.header-test

@@ -22,6 +22,7 @@ header_test := \
 	intel_csr.h \
 	intel_ddi.h \
 	intel_dp.h \
+	intel_dp_link_training.h \
 	intel_dpll_mgr.h \
 	intel_drv.h \
 	intel_dsi.h \

drivers/gpu/drm/i915/intel_ddi.c

@@ -32,6 +32,7 @@
 #include "intel_connector.h"
 #include "intel_ddi.h"
 #include "intel_dp.h"
+#include "intel_dp_link_training.h"
 #include "intel_drv.h"
 #include "intel_dsi.h"
 #include "intel_fifo_underrun.h"

drivers/gpu/drm/i915/intel_dp.c

@@ -47,6 +47,7 @@
 #include "intel_connector.h"
 #include "intel_ddi.h"
 #include "intel_dp.h"
+#include "intel_dp_link_training.h"
 #include "intel_drv.h"
 #include "intel_fifo_underrun.h"
 #include "intel_hdcp.h"

drivers/gpu/drm/i915/intel_dp_link_training.c

@@ -22,6 +22,7 @@
  */
 
 #include "intel_dp.h"
+#include "intel_dp_link_training.h"
 #include "intel_drv.h"
 
 static void

drivers/gpu/drm/i915/intel_dp_link_training.h

+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __INTEL_DP_LINK_TRAINING_H__
+#define __INTEL_DP_LINK_TRAINING_H__
+
+struct intel_dp;
+
+void intel_dp_start_link_train(struct intel_dp *intel_dp);
+void intel_dp_stop_link_train(struct intel_dp *intel_dp);
+
+#endif /* __INTEL_DP_LINK_TRAINING_H__ */

drivers/gpu/drm/i915/intel_drv.h

@@ -1803,10 +1803,6 @@ unsigned int i9xx_plane_max_stride(struct intel_plane *plane,
 				   u32 pixel_format, u64 modifier,
 				   unsigned int rotation);
 
-/* intel_dp_link_training.c */
-void intel_dp_start_link_train(struct intel_dp *intel_dp);
-void intel_dp_stop_link_train(struct intel_dp *intel_dp);
-
 /* intel_vdsc.c */
 int intel_dp_compute_dsc_params(struct intel_dp *intel_dp,
 				struct intel_crtc_state *pipe_config);