[PATCH] drm/ast: add dmabuf/prime buffer sharing support

[oushixiong]

This patch adds ast specific codes for DRM prime feature, this is to
allow for offloading of rending in one direction and outputs in other.

This patch is designed to solve the problem that the AST is not displayed
when the server plug in a discrete graphics graphics card at the same time.
We call the dirty callback function to copy the rendering results of the
discrete graphics card to the ast side by dma-buf.

v1->v2:
  - Fix the comment.
v2->v3:
  - we remove the attach function, add the drm_gem_pin() before dma_buf_vmap(),
    and add the drm_gem_unpin() after the dma_buf_vunmap().

Signed-off-by: oushixiong <oushixiong@xxxxxxxxxx>
---
 drivers/gpu/drm/ast/ast_drv.c  |  27 +++++++
 drivers/gpu/drm/ast/ast_mode.c | 134 ++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/drm_gem.c      |   2 +
 include/drm/drm_gem.h          |   3 +
 4 files changed, 165 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ast/ast_drv.c b/drivers/gpu/drm/ast/ast_drv.c
index 7465c4f0156a..107383a56ca7 100644
--- a/drivers/gpu/drm/ast/ast_drv.c
+++ b/drivers/gpu/drm/ast/ast_drv.c
@@ -28,6 +28,7 @@
 
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/dma-buf.h>
 
 #include <drm/drm_aperture.h>
 #include <drm/drm_atomic_helper.h>
@@ -50,6 +51,29 @@ module_param_named(modeset, ast_modeset, int, 0400);
 
 DEFINE_DRM_GEM_FOPS(ast_fops);
 
+struct drm_gem_object *ast_gem_prime_import(struct drm_device *dev,
+						struct dma_buf *dma_buf)
+{
+	struct drm_gem_vram_object *gbo;
+
+	gbo = drm_gem_vram_of_gem(dma_buf->priv);
+	if (gbo->bo.base.dev == dev) {
+		/*
+		* Importing dmabuf exported from out own gem increases
+		* refcount on gem itself instead of f_count of dmabuf.
+		*/
+		drm_gem_object_get(&gbo->bo.base);
+		return &gbo->bo.base;
+	}
+
+	gbo = drm_gem_vram_create(dev, dma_buf->size, 0);
+	if (IS_ERR(gbo))
+		return NULL;
+
+	get_dma_buf(dma_buf);
+	return &gbo->bo.base;
+}
+
 static const struct drm_driver ast_driver = {
 	.driver_features = DRIVER_ATOMIC |
 			   DRIVER_GEM |
@@ -63,6 +87,9 @@ static const struct drm_driver ast_driver = {
 	.minor = DRIVER_MINOR,
 	.patchlevel = DRIVER_PATCHLEVEL,
 
+	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+	.gem_prime_import = ast_gem_prime_import,
+
 	DRM_GEM_VRAM_DRIVER
 };
 
diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
index 45b56b39ad47..c81a6148b6df 100644
--- a/drivers/gpu/drm/ast/ast_mode.c
+++ b/drivers/gpu/drm/ast/ast_mode.c
@@ -48,6 +48,8 @@
 #include "ast_drv.h"
 #include "ast_tables.h"
 
+MODULE_IMPORT_NS(DMA_BUF);
+
 static inline void ast_load_palette_index(struct ast_private *ast,
 				     u8 index, u8 red, u8 green,
 				     u8 blue)
@@ -1535,8 +1537,138 @@ static const struct drm_mode_config_helper_funcs ast_mode_config_helper_funcs =
 	.atomic_commit_tail = drm_atomic_helper_commit_tail_rpm,
 };
 
+static int ast_handle_damage(struct drm_framebuffer *fb, int x, int y,
+					int width, int height)
+{
+	struct drm_gem_vram_object *dst_bo = NULL;
+	void *dst = NULL;
+	int ret = 0, i;
+	unsigned long offset = 0;
+	bool unmap = false;
+	unsigned int bytesPerPixel;
+	struct iosys_map map;
+	struct iosys_map dmabuf_map;
+
+	bytesPerPixel = fb->format->cpp[0];
+
+	if (!fb->obj[0]->dma_buf)
+		return -EINVAL;
+
+	if (!fb->obj[0]->dma_buf->vmap_ptr.vaddr) {
+		ret = drm_gem_pin(fb->obj[0]->dma_buf->priv);
+		if (ret)
+			return ret;
+		ret = dma_buf_vmap(fb->obj[0]->dma_buf, &dmabuf_map);
+		if (ret)
+			goto err_vmap_dmabuf;
+	} else
+		dmabuf_map.vaddr = fb->obj[0]->dma_buf->vmap_ptr.vaddr;
+
+	dst_bo = drm_gem_vram_of_gem(fb->obj[0]);
+
+	ret = drm_gem_vram_pin(dst_bo, 0);
+	if (ret) {
+		DRM_ERROR("ast_bo_pin failed\n");
+		goto err_ast_pin;
+	}
+
+	if (!dst_bo->map.vaddr) {
+		ret = drm_gem_vram_vmap(dst_bo, &map);
+		if (ret) {
+			DRM_ERROR("failed to vmap fbcon\n");
+			goto err_vmap_ast_bo;
+		}
+		unmap = true;
+	}
+	dst = dst_bo->map.vaddr;
+
+	for (i = y; i < y + height; i++) {
+		offset = i * fb->pitches[0] + (x * bytesPerPixel);
+		memcpy_toio(dst + offset, dmabuf_map.vaddr + offset,
+			width * bytesPerPixel);
+	}
+
+	if (unmap)
+		drm_gem_vram_vunmap(dst_bo, &map);
+
+	drm_gem_vram_unpin(dst_bo);
+	return 0;
+
+err_vmap_ast_bo:
+	drm_gem_vram_unpin(dst_bo);
+err_ast_pin:
+err_vmap_dmabuf:
+	drm_gem_unpin(fb->obj[0]->dma_buf->priv);
+	return ret;
+}
+
+
+static int ast_user_framebuffer_dirty(struct drm_framebuffer *fb,
+				struct drm_file *file,
+				unsigned int flags,
+				unsigned int color,
+				struct drm_clip_rect *clips,
+				unsigned int num_clips)
+{
+	int i, ret = 0;
+
+	drm_modeset_lock_all(fb->dev);
+	if (fb->obj[0]->dma_buf) {
+		ret = dma_buf_begin_cpu_access(fb->obj[0]->dma_buf,
+				DMA_FROM_DEVICE);
+		if (ret)
+			goto unlock;
+	}
+
+	for (i = 0; i < num_clips; i++) {
+		ret = ast_handle_damage(fb, clips[i].x1, clips[i].y1,
+				clips[i].x2 - clips[i].x1, clips[i].y2 - clips[i].y1);
+		if (ret)
+			break;
+	}
+
+	if (fb->obj[0]->dma_buf) {
+		dma_buf_end_cpu_access(fb->obj[0]->dma_buf,
+				DMA_FROM_DEVICE);
+	}
+
+unlock:
+	drm_modeset_unlock_all(fb->dev);
+
+	return ret;
+}
+
+static void ast_user_framebuffer_destroy(struct drm_framebuffer *fb)
+{
+	struct iosys_map dmabuf_map;
+
+	if (fb->obj[0]->dma_buf) {
+		dmabuf_map.is_iomem = fb->obj[0]->dma_buf->vmap_ptr.is_iomem;
+		dmabuf_map.vaddr = fb->obj[0]->dma_buf->vmap_ptr.vaddr;
+		if (dmabuf_map.vaddr)
+			dma_buf_vunmap(fb->obj[0]->dma_buf, &dmabuf_map);
+		drm_gem_unpin(fb->obj[0]->dma_buf->priv);
+	}
+
+	drm_gem_fb_destroy(fb);
+}
+
+static const struct drm_framebuffer_funcs ast_gem_fb_funcs_dirtyfb = {
+	.destroy	= ast_user_framebuffer_destroy,
+	.create_handle	= drm_gem_fb_create_handle,
+	.dirty		= ast_user_framebuffer_dirty,
+};
+
+static struct drm_framebuffer *
+ast_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
+				const struct drm_mode_fb_cmd2 *mode_cmd)
+{
+	return drm_gem_fb_create_with_funcs(dev, file, mode_cmd,
+					&ast_gem_fb_funcs_dirtyfb);
+}
+
 static const struct drm_mode_config_funcs ast_mode_config_funcs = {
-	.fb_create = drm_gem_fb_create,
+	.fb_create = ast_gem_fb_create_with_dirty,
 	.mode_valid = drm_vram_helper_mode_valid,
 	.atomic_check = drm_atomic_helper_check,
 	.atomic_commit = drm_atomic_helper_commit,
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 56fb87885146..3a4f5137abc5 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1159,12 +1159,14 @@ int drm_gem_pin(struct drm_gem_object *obj)
 	else
 		return 0;
 }
+EXPORT_SYMBOL(drm_gem_pin);
 
 void drm_gem_unpin(struct drm_gem_object *obj)
 {
 	if (obj->funcs->unpin)
 		obj->funcs->unpin(obj);
 }
+EXPORT_SYMBOL(drm_gem_unpin);
 
 int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)
 {
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index e2941cee14b6..30c4366968bf 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -352,6 +352,9 @@ int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
 		     struct vm_area_struct *vma);
 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma);
 
+int drm_gem_pin(struct drm_gem_object *obj);
+void drm_gem_unpin(struct drm_gem_object *obj);
+
 /**
  * drm_gem_object_get - acquire a GEM buffer object reference
  * @obj: GEM buffer object
-- 
2.17.1


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