Re: [PATCH v3] drm/ast: add dmabuf/prime buffer sharing support
From: oushixiong
Date: Wed Sep 07 2022 - 06:14:28 EST
Hi,
Firstly, the dirty() call back function is called by
drm_mode_dirtyfb_ioctl.
drm_mode_dirtyfb_ioctl
|__ fb->funcs->dirty(fb, file_priv, flags, r->color,clips,
num_clips);
|__ ast_user_framebuffer_dirty
|__ ast_handle_damage
Secondly, due to hardware limitations, the AST display control modules
can not access the dmabuf that in GTT, so it had to copy the data to AST
VRAM, if we do not use the dmabuf , it need to copy data from discrete
card's VRAM to memory,and copy the data from memory to AST VRAM.
Best regards
oushixiong
On 2022/9/7 下午5:40, Thomas Zimmermann wrote:
Hi ,
Am 07.09.22 um 10:10 schrieb Christian König:
Hi Thomas,
I was wondering pretty much the same thing, but then thought that
this might be the first step to direct scanout from DMA-bufs.
If this isn't the case then I to see this rather critically since
that functionality belongs into userspace.
With GEM VRAM helpers, ast currently doesn't support dma-buf sharing.
I do have patches that convert it to GEM SHMEM (for other reasons),
which would also add this functionality.
I intent to post these patches in the coming days. My suggestion is to
merge them first and then see how to go from there.
Best regards
Thomas
Regards,
Christian.
Am 07.09.22 um 09:50 schrieb Thomas Zimmermann:
Hi,
on a more general note, let me say that your patch doesn't seem to
fit the ideas of how buffer sharing is supposed to work. Your patch
does the BMC screen update 'behind the scenes.'
Shouldn't userspace set up the DRM state for mirroring the output of
the discrete card to the BMC?
Best regards
Thomas
Am 01.09.22 um 14:44 schrieb 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 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 gem_prime_import_sg_table callback and use the
gem_prime_import callback, because it just map and access the
buffer
with the CPU. and do not to pin the buffer.
Signed-off-by: oushixiong <oushixiong@xxxxxxxxxx>
Acked-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/ast/ast_drv.c | 27 +++++++
drivers/gpu/drm/ast/ast_mode.c | 125
++++++++++++++++++++++++++++++++-
2 files changed, 151 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/ast/ast_drv.c
b/drivers/gpu/drm/ast/ast_drv.c
index 7465c4f0156a..fd3c4bad2eb4 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);
+static 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..65a4342c5622 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 +1537,129 @@ 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 = dma_buf_vmap(fb->obj[0]->dma_buf, &dmabuf_map);
+ if (ret)
+ return ret;
+ } 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");
+ return ret;
+ }
+
+ if (!dst_bo->map.vaddr) {
+ ret = drm_gem_vram_vmap(dst_bo, &map);
+ if (ret) {
+ drm_gem_vram_unpin(dst_bo);
+ DRM_ERROR("failed to vmap fbcon\n");
+ return ret;
+ }
+ 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;
+}
+
+
+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_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,
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