On Wed, Jan 27, 2021 at 03:05:03PM +0100, Thomas Zimmermann wrote:
> Functions in the atomic commit tail are not allowed to acquire the
> dmabuf's reservation lock. So we cannot legally call the GEM object's
> vmap functionality in atomic_update.
>
> Instead vmap the cursor BO in prepare_fb and vunmap it in cleanup_fb.
> The cursor plane state stores the mapping's address. The pinning of the
> BO is implicitly done by vmap.
>
> As an extra benefit, there's no source of runtime errors left in
> atomic_update.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Did you test this with my dma_fence_signalling annotations patches?
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/vboxvideo/vbox_mode.c | 102 +++++++++++++++++++++-----
> 1 file changed, 82 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
> index dbc0dd53c69e..b5625a7d6cef 100644
> --- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
> +++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
> @@ -324,6 +324,19 @@ static void vbox_primary_atomic_disable(struct drm_plane *plane,
> old_state->src_y >> 16);
> }
>
> +struct vbox_cursor_plane_state {
> + struct drm_plane_state base;
> +
> + /* Transitional state - do not export or duplicate */
> +
> + struct dma_buf_map map;
> +};
> +
> +static struct vbox_cursor_plane_state *to_vbox_cursor_plane_state(struct drm_plane_state *state)
> +{
> + return container_of(state, struct vbox_cursor_plane_state, base);
> +}
> +
> static int vbox_cursor_atomic_check(struct drm_plane *plane,
> struct drm_plane_state *new_state)
> {
> @@ -381,14 +394,13 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
> container_of(plane->dev, struct vbox_private, ddev);
> struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
> struct drm_framebuffer *fb = plane->state->fb;
> - struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
> u32 width = plane->state->crtc_w;
> u32 height = plane->state->crtc_h;
> + struct vbox_cursor_plane_state *vbox_state = to_vbox_cursor_plane_state(plane->state);
> + struct dma_buf_map map = vbox_state->map;
> + u8 *src = map.vaddr; /* TODO: Use mapping abstraction properly */
> size_t data_size, mask_size;
> u32 flags;
> - struct dma_buf_map map;
> - int ret;
> - u8 *src;
>
> /*
> * VirtualBox uses the host windowing system to draw the cursor so
> @@ -401,17 +413,6 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
>
> vbox_crtc->cursor_enabled = true;
>
> - ret = drm_gem_vram_vmap(gbo, &map);
> - if (ret) {
> - /*
> - * BUG: we should have pinned the BO in prepare_fb().
> - */
> - mutex_unlock(&vbox->hw_mutex);
> - DRM_WARN("Could not map cursor bo, skipping update\n");
> - return;
> - }
> - src = map.vaddr; /* TODO: Use mapping abstraction properly */
> -
> /*
> * The mask must be calculated based on the alpha
> * channel, one bit per ARGB word, and must be 32-bit
> @@ -421,7 +422,6 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
> data_size = width * height * 4 + mask_size;
>
> copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
> - drm_gem_vram_vunmap(gbo, &map);
>
> flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
> VBOX_MOUSE_POINTER_ALPHA;
> @@ -458,6 +458,43 @@ static void vbox_cursor_atomic_disable(struct drm_plane *plane,
> mutex_unlock(&vbox->hw_mutex);
> }
>
> +static int vbox_cursor_prepare_fb(struct drm_plane *plane, struct drm_plane_state *new_state)
> +{
> + struct vbox_cursor_plane_state *new_vbox_state = to_vbox_cursor_plane_state(new_state);
> + struct drm_framebuffer *fb = new_state->fb;
> + struct drm_gem_vram_object *gbo;
> + struct dma_buf_map map;
> + int ret;
> +
> + if (!fb)
> + return 0;
> +
> + gbo = drm_gem_vram_of_gem(fb->obj[0]);
> +
> + ret = drm_gem_vram_vmap(gbo, &map);
> + if (ret)
> + return ret;
> +
> + new_vbox_state->map = map;
> +
> + return 0;
> +}
> +
> +static void vbox_cursor_cleanup_fb(struct drm_plane *plane, struct drm_plane_state *old_state)
> +{
> + struct vbox_cursor_plane_state *old_vbox_state = to_vbox_cursor_plane_state(old_state);
> + struct drm_framebuffer *fb = old_state->fb;
> + struct dma_buf_map map = old_vbox_state->map;
> + struct drm_gem_vram_object *gbo;
> +
> + if (!fb)
> + return;
> +
> + gbo = drm_gem_vram_of_gem(fb->obj[0]);
> +
> + drm_gem_vram_vunmap(gbo, &map);
> +}
> +
> static const u32 vbox_cursor_plane_formats[] = {
> DRM_FORMAT_ARGB8888,
> };
> @@ -466,17 +503,42 @@ static const struct drm_plane_helper_funcs vbox_cursor_helper_funcs = {
> .atomic_check = vbox_cursor_atomic_check,
> .atomic_update = vbox_cursor_atomic_update,
> .atomic_disable = vbox_cursor_atomic_disable,
> - .prepare_fb = drm_gem_vram_plane_helper_prepare_fb,
> - .cleanup_fb = drm_gem_vram_plane_helper_cleanup_fb,
> + .prepare_fb = vbox_cursor_prepare_fb,
> + .cleanup_fb = vbox_cursor_cleanup_fb,
> };
>
> +static struct drm_plane_state *vbox_cursor_atomic_duplicate_state(struct drm_plane *plane)
> +{
> + struct vbox_cursor_plane_state *new_vbox_state;
> + struct drm_device *dev = plane->dev;
> +
> + if (drm_WARN_ON(dev, !plane->state))
> + return NULL;
> +
> + new_vbox_state = kzalloc(sizeof(*new_vbox_state), GFP_KERNEL);
> + if (!new_vbox_state)
> + return NULL;
> + __drm_atomic_helper_plane_duplicate_state(plane, &new_vbox_state->base);
> +
> + return &new_vbox_state->base;
> +}
> +
> +static void vbox_cursor_atomic_destroy_state(struct drm_plane *plane,
> + struct drm_plane_state *state)
> +{
> + struct vbox_cursor_plane_state *vbox_state = to_vbox_cursor_plane_state(state);
> +
> + __drm_atomic_helper_plane_destroy_state(&vbox_state->base);
> + kfree(vbox_state);
> +}
> +
> static const struct drm_plane_funcs vbox_cursor_plane_funcs = {
> .update_plane = drm_atomic_helper_update_plane,
> .disable_plane = drm_atomic_helper_disable_plane,
> .destroy = drm_primary_helper_destroy,
> .reset = drm_atomic_helper_plane_reset,
> - .atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
> - .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
> + .atomic_duplicate_state = vbox_cursor_atomic_duplicate_state,
> + .atomic_destroy_state = vbox_cursor_atomic_destroy_state,
> };
>
> static const u32 vbox_primary_plane_formats[] = {
>
> base-commit: 3836b7fdfad40e2bac5dc882332f42bed6942cf4
> prerequisite-patch-id: c2b2f08f0eccc9f5df0c0da49fa1d36267deb11d
> --
> 2.30.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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