drm/i915 & drm/xe: save struct drm_device to drvdata

In the future, the display code shall not have any idea about struct
xe_device or struct drm_i915_private, but will need to get at the struct
drm_device via drvdata. Store the struct drm_device pointer to drvdata
instead of the driver specific pointer.

Avoid passing NULL to container_of() via to_i915()/to_xe_device(). (It
does return NULL for NULL pointers when the offset happens to be 0, but
otherwise returns garbage pointers for NULL.)
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/946805b32e38d4785880cc7857e01e6a309126a9.1724942754.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_driver.c

@@ -723,7 +723,7 @@ i915_driver_create(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (IS_ERR(i915))
 		return i915;
 
-	pci_set_drvdata(pdev, i915);
+	pci_set_drvdata(pdev, &i915->drm);
 
 	/* Device parameters start as a copy of module parameters. */
 	i915_params_copy(&i915->params, &i915_modparams);

drivers/gpu/drm/i915/i915_drv.h

@@ -365,12 +365,16 @@ static inline struct drm_i915_private *to_i915(const struct drm_device *dev)
 
 static inline struct drm_i915_private *kdev_to_i915(struct device *kdev)
 {
-	return dev_get_drvdata(kdev);
+	struct drm_device *drm = dev_get_drvdata(kdev);
+
+	return drm ? to_i915(drm) : NULL;
 }
 
 static inline struct drm_i915_private *pdev_to_i915(struct pci_dev *pdev)
 {
-	return pci_get_drvdata(pdev);
+	struct drm_device *drm = pci_get_drvdata(pdev);
+
+	return drm ? to_i915(drm) : NULL;
 }
 
 static inline struct intel_gt *to_gt(const struct drm_i915_private *i915)

drivers/gpu/drm/i915/selftests/mock_gem_device.c

@@ -172,7 +172,7 @@ struct drm_i915_private *mock_gem_device(void)
 		return NULL;
 	}
 
-	pci_set_drvdata(pdev, i915);
+	pci_set_drvdata(pdev, &i915->drm);
 
 	/* Device parameters start as a copy of module parameters. */
 	i915_params_copy(&i915->params, &i915_modparams);

drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h

@@ -23,7 +23,9 @@ static inline struct drm_i915_private *to_i915(const struct drm_device *dev)
 
 static inline struct drm_i915_private *kdev_to_i915(struct device *kdev)
 {
-	return dev_get_drvdata(kdev);
+	struct drm_device *drm = dev_get_drvdata(kdev);
+
+	return drm ? to_i915(drm) : NULL;
 }
 
 #define IS_PLATFORM(xe, x) ((xe)->info.platform == x)

drivers/gpu/drm/xe/xe_device.h

@@ -17,12 +17,16 @@ static inline struct xe_device *to_xe_device(const struct drm_device *dev)
 
 static inline struct xe_device *kdev_to_xe_device(struct device *kdev)
 {
-	return dev_get_drvdata(kdev);
+	struct drm_device *drm = dev_get_drvdata(kdev);
+
+	return drm ? to_xe_device(drm) : NULL;
 }
 
 static inline struct xe_device *pdev_to_xe_device(struct pci_dev *pdev)
 {
-	return pci_get_drvdata(pdev);
+	struct drm_device *drm = pci_get_drvdata(pdev);
+
+	return drm ? to_xe_device(drm) : NULL;
 }
 
 static inline struct xe_device *xe_device_const_cast(const struct xe_device *xe)

drivers/gpu/drm/xe/xe_pci.c

@@ -793,7 +793,7 @@ static int xe_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (IS_ERR(xe))
 		return PTR_ERR(xe);
 
-	pci_set_drvdata(pdev, xe);
+	pci_set_drvdata(pdev, &xe->drm);
 
 	xe_pm_assert_unbounded_bridge(xe);
 	subplatform_desc = find_subplatform(xe, desc);