On 8/17/2023 7:33 PM, Dmitry Osipenko wrote:
On 7/13/23 01:44, Dongwon Kim wrote:
This helper is needed for framebuffer synchronization. Old framebuffer data
is often displayed on the guest display without this helper.
Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Cc: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx>
---
drivers/gpu/drm/virtio/virtgpu_plane.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index a063f06ab6c5..e197299489ce 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -26,6 +26,7 @@
#include <drm/drm_atomic_helper.h>
#include <drm/drm_damage_helper.h>
#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_atomic_helper.h>
#include "virtgpu_drv.h"
@@ -271,6 +272,9 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
vgfb = to_virtio_gpu_framebuffer(new_state->fb);
vgplane_st = to_virtio_gpu_plane_state(new_state);
bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
+
+ drm_gem_plane_helper_prepare_fb(plane, new_state);
The implicit display BO sync should happen on a host side, unless you're
rendering with Venus and then displaying with virgl. Doing it on guest
side should be a major performance hit. Please provide a complete
description of your setup: what VMM you use, config options, what tests
you're running.
We use virtio-gpu as a kms device while using i915 as the render device in our setup.
And we use QEMU as VMM. Virtio-gpu driver flushes the scanout to QEMU as a blob resource
(reference to the buffer). QEMU then creates a dmabuf using udmabuf for the blob
then renders it as a texture using OGL. The test I ran is simple. Just starting terminal
app and typing things to see if there is any frame regression. I believe this helper is
required since the BO on the guest is basically dmabuf that is being shared between i915
and virtio-gpu driver. I didn't think about the performance impact. If the impact is
too much and that is not acceptable, is there any other suggestions or some tests I can try?
Thanks!
