[RESEND 5/6] drm/i915/display: add struct drm_device to struct intel_display conversion function

[Jani Nikula]

Add a __drm_to_display() conversion function to hide the to_i915() usage
and the implicit dependency on i915_drv.h from intel_display_types.h.

The goal is for this implementation to be a transitional helper
only. One idea I've floated around in the past would be to require a
struct intel_display pointer member to be placed right after struct
drm_device member in struct drm_i915_private and struct xe_device
[1][2].

[1] https://lore.kernel.org/r/7777ff70e2be0663de4398aa6f75f0c54146cbfc.1709727127.git.jani.nikula@intel.com
[2] https://lore.kernel.org/r/0b9459da6c8cba0f74bf2781d69182fa6801cd97.1709727127.git.jani.nikula@intel.com

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display_conversion.c | 5 +++++
 drivers/gpu/drm/i915/display/intel_display_conversion.h | 3 ++-
 drivers/gpu/drm/i915/display/intel_display_types.h      | 3 ++-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display_conversion.c b/drivers/gpu/drm/i915/display/intel_display_conversion.c
index bdd947f5ccd8..0578b68404da 100644
--- a/drivers/gpu/drm/i915/display/intel_display_conversion.c
+++ b/drivers/gpu/drm/i915/display/intel_display_conversion.c
@@ -7,3 +7,8 @@ struct intel_display *__i915_to_display(struct drm_i915_private *i915)
 {
 	return &i915->display;
 }
+
+struct intel_display *__drm_to_display(struct drm_device *drm)
+{
+	return __i915_to_display(to_i915(drm));
+}
diff --git a/drivers/gpu/drm/i915/display/intel_display_conversion.h b/drivers/gpu/drm/i915/display/intel_display_conversion.h
index 790d0be698dc..46c7208d42ba 100644
--- a/drivers/gpu/drm/i915/display/intel_display_conversion.h
+++ b/drivers/gpu/drm/i915/display/intel_display_conversion.h
@@ -8,11 +8,12 @@
 #ifndef __INTEL_DISPLAY_CONVERSION__
 #define __INTEL_DISPLAY_CONVERSION__
 
+struct drm_device;
 struct drm_i915_private;
 struct intel_display;
 
 struct intel_display *__i915_to_display(struct drm_i915_private *i915);
-
+struct intel_display *__drm_to_display(struct drm_device *drm);
 /*
  * Transitional macro to optionally convert struct drm_i915_private * to struct
  * intel_display *, also accepting the latter.
diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
index 339e4b0f7698..2098e14b7ae7 100644
--- a/drivers/gpu/drm/i915/display/intel_display_types.h
+++ b/drivers/gpu/drm/i915/display/intel_display_types.h
@@ -45,6 +45,7 @@
 #include "i915_vma_types.h"
 #include "intel_bios.h"
 #include "intel_display.h"
+#include "intel_display_conversion.h"
 #include "intel_display_limits.h"
 #include "intel_display_power.h"
 #include "intel_dpll_mgr.h"
@@ -2086,7 +2087,7 @@ to_intel_frontbuffer(struct drm_framebuffer *fb)
  * intel_display pointer.
  */
 #define __drm_device_to_intel_display(p) \
-	((p) ? &to_i915(p)->display : NULL)
+	((p) ? __drm_to_display(p) : NULL)
 #define __device_to_intel_display(p)				\
 	__drm_device_to_intel_display(dev_get_drvdata(p))
 #define __pci_dev_to_intel_display(p)				\
-- 
2.39.5