1 files changed, 432 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
new file mode 100644
index 000000000000..a005c5a0ba46
--- /dev/null
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/dma-resv.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_atomic_uapi.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#include "drm_internal.h"
+
+/**
+ * DOC: overview
+ *
+ * The GEM atomic helpers library implements generic atomic-commit
+ * functions for drivers that use GEM objects. Currently, it provides
+ * synchronization helpers, and plane state and framebuffer BO mappings
+ * for planes with shadow buffers.
+ *
+ * Before scanout, a plane's framebuffer needs to be synchronized with
+ * possible writers that draw into the framebuffer. All drivers should
+ * call drm_gem_plane_helper_prepare_fb() from their implementation of
+ * struct &drm_plane_helper.prepare_fb . It sets the plane's fence from
+ * the framebuffer so that the DRM core can synchronize access automatically.
+ *
+ * drm_gem_plane_helper_prepare_fb() can also be used directly as
+ * implementation of prepare_fb. For drivers based on
+ * struct drm_simple_display_pipe, drm_gem_simple_display_pipe_prepare_fb()
+ * provides equivalent functionality.
+ *
+ * .. code-block:: c
+ *
+ *	#include <drm/drm_gem_atomic_helper.h>
+ *
+ *	struct drm_plane_helper_funcs driver_plane_helper_funcs = {
+ *		...,
+ *		. prepare_fb = drm_gem_plane_helper_prepare_fb,
+ *	};
+ *
+ *	struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
+ *		...,
+ *		. prepare_fb = drm_gem_simple_display_pipe_prepare_fb,
+ *	};
+ *
+ * A driver using a shadow buffer copies the content of the shadow buffers
+ * into the HW's framebuffer memory during an atomic update. This requires
+ * a mapping of the shadow buffer into kernel address space. The mappings
+ * cannot be established by commit-tail functions, such as atomic_update,
+ * as this would violate locking rules around dma_buf_vmap().
+ *
+ * The helpers for shadow-buffered planes establish and release mappings,
+ * and provide struct drm_shadow_plane_state, which stores the plane's mapping
+ * for commit-tail functons.
+ *
+ * Shadow-buffered planes can easily be enabled by using the provided macros
+ * %DRM_GEM_SHADOW_PLANE_FUNCS and %DRM_GEM_SHADOW_PLANE_HELPER_FUNCS.
+ * These macros set up the plane and plane-helper callbacks to point to the
+ * shadow-buffer helpers.
+ *
+ * .. code-block:: c
+ *
+ *	#include <drm/drm_gem_atomic_helper.h>
+ *
+ *	struct drm_plane_funcs driver_plane_funcs = {
+ *		...,
+ *		DRM_GEM_SHADOW_PLANE_FUNCS,
+ *	};
+ *
+ *	struct drm_plane_helper_funcs driver_plane_helper_funcs = {
+ *		...,
+ *		DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+ *	};
+ *
+ * In the driver's atomic-update function, shadow-buffer mappings are available
+ * from the plane state. Use to_drm_shadow_plane_state() to upcast from
+ * struct drm_plane_state.
+ *
+ * .. code-block:: c
+ *
+ *	void driver_plane_atomic_update(struct drm_plane *plane,
+ *					struct drm_plane_state *old_plane_state)
+ *	{
+ *		struct drm_plane_state *plane_state = plane->state;
+ *		struct drm_shadow_plane_state *shadow_plane_state =
+ *			to_drm_shadow_plane_state(plane_state);
+ *
+ *		// access shadow buffer via shadow_plane_state->map
+ *	}
+ *
+ * A mapping address for each of the framebuffer's buffer object is stored in
+ * struct &drm_shadow_plane_state.map. The mappings are valid while the state
+ * is being used.
+ *
+ * Drivers that use struct drm_simple_display_pipe can use
+ * %DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS to initialize the rsp
+ * callbacks. Access to shadow-buffer mappings is similar to regular
+ * atomic_update.
+ *
+ * .. code-block:: c
+ *
+ *	struct drm_simple_display_pipe_funcs driver_pipe_funcs = {
+ *		...,
+ *		DRM_GEM_SIMPLE_DISPLAY_PIPE_SHADOW_PLANE_FUNCS,
+ *	};
+ *
+ *	void driver_pipe_enable(struct drm_simple_display_pipe *pipe,
+ *				struct drm_crtc_state *crtc_state,
+ *				struct drm_plane_state *plane_state)
+ *	{
+ *		struct drm_shadow_plane_state *shadow_plane_state =
+ *			to_drm_shadow_plane_state(plane_state);
+ *
+ *		// access shadow buffer via shadow_plane_state->map
+ *	}
+ */
+
+/*
+ * Plane Helpers
+ */
+
+/**
+ * drm_gem_plane_helper_prepare_fb() - Prepare a GEM backed framebuffer
+ * @plane: Plane
+ * @state: Plane state the fence will be attached to
+ *
+ * This function extracts the exclusive fence from &drm_gem_object.resv and
+ * attaches it to plane state for the atomic helper to wait on. This is
+ * necessary to correctly implement implicit synchronization for any buffers
+ * shared as a struct &dma_buf. This function can be used as the
+ * &drm_plane_helper_funcs.prepare_fb callback.
+ *
+ * There is no need for &drm_plane_helper_funcs.cleanup_fb hook for simple
+ * GEM based framebuffer drivers which have their buffers always pinned in
+ * memory.
+ *
+ * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
+ * explicit fencing in atomic modeset updates.
+ */
+int drm_gem_plane_helper_prepare_fb(struct drm_plane *plane, struct drm_plane_state *state)
+{
+	struct drm_gem_object *obj;
+	struct dma_fence *fence;
+
+	if (!state->fb)
+		return 0;
+
+	obj = drm_gem_fb_get_obj(state->fb, 0);
+	fence = dma_resv_get_excl_rcu(obj->resv);
+	drm_atomic_set_fence_for_plane(state, fence);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(drm_gem_plane_helper_prepare_fb);
+
+/**
+ * drm_gem_simple_display_pipe_prepare_fb - prepare_fb helper for &drm_simple_display_pipe
+ * @pipe: Simple display pipe
+ * @plane_state: Plane state
+ *
+ * This function uses drm_gem_plane_helper_prepare_fb() to extract the exclusive fence
+ * from &drm_gem_object.resv and attaches it to plane state for the atomic
+ * helper to wait on. This is necessary to correctly implement implicit
+ * synchronization for any buffers shared as a struct &dma_buf. Drivers can use
+ * this as their &drm_simple_display_pipe_funcs.prepare_fb callback.
+ *
+ * See drm_atomic_set_fence_for_plane() for a discussion of implicit and
+ * explicit fencing in atomic modeset updates.
+ */
+int drm_gem_simple_display_pipe_prepare_fb(struct drm_simple_display_pipe *pipe,
+					   struct drm_plane_state *plane_state)
+{
+	return drm_gem_plane_helper_prepare_fb(&pipe->plane, plane_state);
+}
+EXPORT_SYMBOL(drm_gem_simple_display_pipe_prepare_fb);
+
+/*
+ * Shadow-buffered Planes
+ */
+
+/**
+ * drm_gem_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
+ * @plane: the plane
+ *
+ * This function implements struct &drm_plane_funcs.atomic_duplicate_state for
+ * shadow-buffered planes. It assumes the existing state to be of type
+ * struct drm_shadow_plane_state and it allocates the new state to be of this
+ * type.
+ *
+ * The function does not duplicate existing mappings of the shadow buffers.
+ * Mappings are maintained during the atomic commit by the plane's prepare_fb
+ * and cleanup_fb helpers. See drm_gem_prepare_shadow_fb() and drm_gem_cleanup_shadow_fb()
+ * for corresponding helpers.
+ *
+ * Returns:
+ * A pointer to a new plane state on success, or NULL otherwise.
+ */
+struct drm_plane_state *
+drm_gem_duplicate_shadow_plane_state(struct drm_plane *plane)
+{
+	struct drm_plane_state *plane_state = plane->state;
+	struct drm_shadow_plane_state *new_shadow_plane_state;
+
+	if (!plane_state)
+		return NULL;
+
+	new_shadow_plane_state = kzalloc(sizeof(*new_shadow_plane_state), GFP_KERNEL);
+	if (!new_shadow_plane_state)
+		return NULL;
+	__drm_atomic_helper_plane_duplicate_state(plane, &new_shadow_plane_state->base);
+
+	return &new_shadow_plane_state->base;
+}
+EXPORT_SYMBOL(drm_gem_duplicate_shadow_plane_state);
+
+/**
+ * drm_gem_destroy_shadow_plane_state - deletes shadow-buffered plane state
+ * @plane: the plane
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct &drm_plane_funcs.atomic_destroy_state
+ * for shadow-buffered planes. It expects that mappings of shadow buffers
+ * have been released already.
+ */
+void drm_gem_destroy_shadow_plane_state(struct drm_plane *plane,
+					struct drm_plane_state *plane_state)
+{
+	struct drm_shadow_plane_state *shadow_plane_state =
+		to_drm_shadow_plane_state(plane_state);
+
+	__drm_atomic_helper_plane_destroy_state(&shadow_plane_state->base);
+	kfree(shadow_plane_state);
+}
+EXPORT_SYMBOL(drm_gem_destroy_shadow_plane_state);
+
+/**
+ * drm_gem_reset_shadow_plane - resets a shadow-buffered plane
+ * @plane: the plane
+ *
+ * This function implements struct &drm_plane_funcs.reset_plane for
+ * shadow-buffered planes. It assumes the current plane state to be
+ * of type struct drm_shadow_plane and it allocates the new state of
+ * this type.
+ */
+void drm_gem_reset_shadow_plane(struct drm_plane *plane)
+{
+	struct drm_shadow_plane_state *shadow_plane_state;
+
+	if (plane->state) {
+		drm_gem_destroy_shadow_plane_state(plane, plane->state);
+		plane->state = NULL; /* must be set to NULL here */
+	}
+
+	shadow_plane_state = kzalloc(sizeof(*shadow_plane_state), GFP_KERNEL);
+	if (!shadow_plane_state)
+		return;
+	__drm_atomic_helper_plane_reset(plane, &shadow_plane_state->base);
+}
+EXPORT_SYMBOL(drm_gem_reset_shadow_plane);
+
+/**
+ * drm_gem_prepare_shadow_fb - prepares shadow framebuffers
+ * @plane: the plane
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct &drm_plane_helper_funcs.prepare_fb. It
+ * maps all buffer objects of the plane's framebuffer into kernel address
+ * space and stores them in &struct drm_shadow_plane_state.map. The
+ * framebuffer will be synchronized as part of the atomic commit.
+ *
+ * See drm_gem_cleanup_shadow_fb() for cleanup.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
+{
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct drm_gem_object *obj;
+	struct dma_buf_map map;
+	int ret;
+	size_t i;
+
+	if (!fb)
+		return 0;
+
+	ret = drm_gem_plane_helper_prepare_fb(plane, plane_state);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(shadow_plane_state->map); ++i) {
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		ret = drm_gem_vmap(obj, &map);
+		if (ret)
+			goto err_drm_gem_vunmap;
+		shadow_plane_state->map[i] = map;
+	}
+
+	return 0;
+
+err_drm_gem_vunmap:
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &shadow_plane_state->map[i]);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
+
+/**
+ * drm_gem_cleanup_shadow_fb - releases shadow framebuffers
+ * @plane: the plane
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct &drm_plane_helper_funcs.cleanup_fb.
+ * This function unmaps all buffer objects of the plane's framebuffer.
+ *
+ * See drm_gem_prepare_shadow_fb() for more inforamtion.
+ */
+void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
+{
+	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+	struct drm_framebuffer *fb = plane_state->fb;
+	size_t i = ARRAY_SIZE(shadow_plane_state->map);
+	struct drm_gem_object *obj;
+
+	if (!fb)
+		return;
+
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &shadow_plane_state->map[i]);
+	}
+}
+EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
+
+/**
+ * drm_gem_simple_kms_prepare_shadow_fb - prepares shadow framebuffers
+ * @pipe: the simple display pipe
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct drm_simple_display_funcs.prepare_fb. It
+ * maps all buffer objects of the plane's framebuffer into kernel address
+ * space and stores them in struct drm_shadow_plane_state.map. The
+ * framebuffer will be synchronized as part of the atomic commit.
+ *
+ * See drm_gem_simple_kms_cleanup_shadow_fb() for cleanup.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drm_gem_simple_kms_prepare_shadow_fb(struct drm_simple_display_pipe *pipe,
+					 struct drm_plane_state *plane_state)
+{
+	return drm_gem_prepare_shadow_fb(&pipe->plane, plane_state);
+}
+EXPORT_SYMBOL(drm_gem_simple_kms_prepare_shadow_fb);
+
+/**
+ * drm_gem_simple_kms_cleanup_shadow_fb - releases shadow framebuffers
+ * @pipe: the simple display pipe
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct drm_simple_display_funcs.cleanup_fb.
+ * This function unmaps all buffer objects of the plane's framebuffer.
+ *
+ * See drm_gem_simple_kms_prepare_shadow_fb().
+ */
+void drm_gem_simple_kms_cleanup_shadow_fb(struct drm_simple_display_pipe *pipe,
+					  struct drm_plane_state *plane_state)
+{
+	drm_gem_cleanup_shadow_fb(&pipe->plane, plane_state);
+}
+EXPORT_SYMBOL(drm_gem_simple_kms_cleanup_shadow_fb);
+
+/**
+ * drm_gem_simple_kms_reset_shadow_plane - resets a shadow-buffered plane
+ * @pipe: the simple display pipe
+ *
+ * This function implements struct drm_simple_display_funcs.reset_plane
+ * for shadow-buffered planes.
+ */
+void drm_gem_simple_kms_reset_shadow_plane(struct drm_simple_display_pipe *pipe)
+{
+	drm_gem_reset_shadow_plane(&pipe->plane);
+}
+EXPORT_SYMBOL(drm_gem_simple_kms_reset_shadow_plane);
+
+/**
+ * drm_gem_simple_kms_duplicate_shadow_plane_state - duplicates shadow-buffered plane state
+ * @pipe: the simple display pipe
+ *
+ * This function implements struct drm_simple_display_funcs.duplicate_plane_state
+ * for shadow-buffered planes. It does not duplicate existing mappings of the shadow
+ * buffers. Mappings are maintained during the atomic commit by the plane's prepare_fb
+ * and cleanup_fb helpers.
+ *
+ * Returns:
+ * A pointer to a new plane state on success, or NULL otherwise.
+ */
+struct drm_plane_state *
+drm_gem_simple_kms_duplicate_shadow_plane_state(struct drm_simple_display_pipe *pipe)
+{
+	return drm_gem_duplicate_shadow_plane_state(&pipe->plane);
+}
+EXPORT_SYMBOL(drm_gem_simple_kms_duplicate_shadow_plane_state);
+
+/**
+ * drm_gem_simple_kms_destroy_shadow_plane_state - resets shadow-buffered plane state
+ * @pipe: the simple display pipe
+ * @plane_state: the plane state of type struct drm_shadow_plane_state
+ *
+ * This function implements struct drm_simple_display_funcs.destroy_plane_state
+ * for shadow-buffered planes. It expects that mappings of shadow buffers
+ * have been released already.
+ */
+void drm_gem_simple_kms_destroy_shadow_plane_state(struct drm_simple_display_pipe *pipe,
+						   struct drm_plane_state *plane_state)
+{
+	drm_gem_destroy_shadow_plane_state(&pipe->plane, plane_state);
+}
+EXPORT_SYMBOL(drm_gem_simple_kms_destroy_shadow_plane_state);