drm/i915: hide mkwrite_device_info() better

The goal has been to just make device info a pointer to static const
data, i.e. the static const structs in i915_pci.c. See [1]. However,
there were issues with intel_device_info_runtime_init() clearing the
display sub-struct of device info on the !HAS_DISPLAY() path, which
consequently disables a lot of display functionality, like it
should. Looks like we'd have to cover all those paths, and maybe
sprinkle HAS_DISPLAY() checks in them, which we haven't gotten around
to.

In the mean time, hide mkwrite_device_info() better within
intel_device_info.c by adding a intel_device_info_driver_create() for
the very early initialization of the device info and initial runtime
info. This also lets us declutter i915_drv.h a bit, and stops promoting
mkwrite_device_info() as something that could be used.

[1] https://lore.kernel.org/r/a0422f0a8ac055f65b7922bcd3119b180a41e79e.1655712106.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230411105643.292416-1-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_driver.c

@@ -718,8 +718,6 @@ i915_driver_create(struct pci_dev *pdev, const struct pci_device_id *ent)
 {
 	const struct intel_device_info *match_info =
 		(struct intel_device_info *)ent->driver_data;
-	struct intel_device_info *device_info;
-	struct intel_runtime_info *runtime;
 	struct drm_i915_private *i915;
 
 	i915 = devm_drm_dev_alloc(&pdev->dev, &i915_drm_driver,
@@ -732,14 +730,8 @@ i915_driver_create(struct pci_dev *pdev, const struct pci_device_id *ent)
 	/* Device parameters start as a copy of module parameters. */
 	i915_params_copy(&i915->params, &i915_modparams);
 
-	/* Setup the write-once "constant" device info */
-	device_info = mkwrite_device_info(i915);
-	memcpy(device_info, match_info, sizeof(*device_info));
-
-	/* Initialize initial runtime info from static const data and pdev. */
-	runtime = RUNTIME_INFO(i915);
-	memcpy(runtime, &INTEL_INFO(i915)->__runtime, sizeof(*runtime));
-	runtime->device_id = pdev->device;
+	/* Set up device info and initial runtime info. */
+	intel_device_info_driver_create(i915, pdev->device, match_info);
 
 	return i915;
 }

drivers/gpu/drm/i915/i915_drv.h

@@ -929,11 +929,4 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
 #define HAS_LMEMBAR_SMEM_STOLEN(i915) (!HAS_LMEM(i915) && \
 				       GRAPHICS_VER_FULL(i915) >= IP_VER(12, 70))
 
-/* intel_device_info.c */
-static inline struct intel_device_info *
-mkwrite_device_info(struct drm_i915_private *dev_priv)
-{
-	return (struct intel_device_info *)INTEL_INFO(dev_priv);
-}
-
 #endif

drivers/gpu/drm/i915/intel_device_info.c

@@ -381,6 +381,13 @@ void intel_device_info_runtime_init_early(struct drm_i915_private *i915)
 	intel_device_info_subplatform_init(i915);
 }
 
+/* FIXME: Remove this, and make device info a const pointer to rodata. */
+static struct intel_device_info *
+mkwrite_device_info(struct drm_i915_private *i915)
+{
+	return (struct intel_device_info *)INTEL_INFO(i915);
+}
+
 /**
  * intel_device_info_runtime_init - initialize runtime info
  * @dev_priv: the i915 device
@@ -548,6 +555,28 @@ void intel_device_info_runtime_init(struct drm_i915_private *dev_priv)
 		dev_priv->drm.driver_features &= ~DRIVER_ATOMIC;
 }
 
+/*
+ * Set up device info and initial runtime info at driver create.
+ *
+ * Note: i915 is only an allocated blob of memory at this point.
+ */
+void intel_device_info_driver_create(struct drm_i915_private *i915,
+				     u16 device_id,
+				     const struct intel_device_info *match_info)
+{
+	struct intel_device_info *info;
+	struct intel_runtime_info *runtime;
+
+	/* Setup the write-once "constant" device info */
+	info = mkwrite_device_info(i915);
+	memcpy(info, match_info, sizeof(*info));
+
+	/* Initialize initial runtime info from static const data and pdev. */
+	runtime = RUNTIME_INFO(i915);
+	memcpy(runtime, &INTEL_INFO(i915)->__runtime, sizeof(*runtime));
+	runtime->device_id = device_id;
+}
+
 void intel_driver_caps_print(const struct intel_driver_caps *caps,
 			     struct drm_printer *p)
 {

drivers/gpu/drm/i915/intel_device_info.h

@@ -316,6 +316,8 @@ struct intel_driver_caps {
 
 const char *intel_platform_name(enum intel_platform platform);
 
+void intel_device_info_driver_create(struct drm_i915_private *i915, u16 device_id,
+				     const struct intel_device_info *match_info);
 void intel_device_info_runtime_init_early(struct drm_i915_private *dev_priv);
 void intel_device_info_runtime_init(struct drm_i915_private *dev_priv);