> -----Original Message----- > From: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> > Sent: Monday, October 23, 2023 5:24 AM > To: Kim, Dongwon <dongwon.kim@xxxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx > Cc: kraxel@xxxxxxxxxx; Kasireddy, Vivek <vivek.kasireddy@xxxxxxxxx> > Subject: Re: [RFC PATCH v2 1/1] drm/virtio: new fence for every plane update > > On 10/3/23 04:00, Dongwon Kim wrote: > > Having a fence linked to a virtio_gpu_framebuffer in the plane update > > sequence would cause conflict when several planes referencing the same > > framebuffer (e.g. Xorg screen covering multi-displays configured for > > an extended mode) and those planes are updated concurrently. So it is > > needed to allocate a fence for every plane state instead of the framebuffer. > > > > The plane state for virtio-gpu, "struct virtio_gpu_plane_state" is > > added for this. This structure represents drm_plane_state and it > > contains the reference to virtio_gpu_fence, which was previously in "struct > virtio_gpu_framebuffer". > > > > "virtio_gpu_plane_duplicate_state" is added as well to create a > > virtio_gpu_plane_state on top of duplicated drm plane state. > > > > Several drm helpers were slightly modified accordingly to use the > > fence in new plane state structure. virtio_gpu_plane_cleanup_fb was > > completely removed as dma_fence_put shouldn't be called here as it can > > mess up with the ref count of the fence. The fence should be put after > > the fence is signaled in virtio_gpu_resource_flush then released in > > virtio_gpu_array_add_fence while the next virtio message is being queued. > > > > Also, the condition for adding fence, (plane->state->fb != > > new_state->fb) was removed since we now allocate a new fence for the > > new plane state even if both old and new planes are pointing to the same > framebuffer. > > > > v2: removed virtio_gpu_plane_duplicate_state as the existing helper, > > drm_atomic_helper_plane_destroy_state does the same. > > > > Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx> > > Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx> > > Cc: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx> > > Signed-off-by: Dongwon Kim <dongwon.kim@xxxxxxxxx> > > --- > > drivers/gpu/drm/virtio/virtgpu_drv.h | 7 +++ > > drivers/gpu/drm/virtio/virtgpu_plane.c | 66 > > +++++++++++++++++--------- > > 2 files changed, 51 insertions(+), 22 deletions(-) > > Please write a guide how to test it. Are you using spice for the multi-display > viewer? [DW] Yeah, let me come up with a simple test case. So we use virtio-gpu as KMS device. It is used to share the guest frame with QEMU. SPICE is one of client solutions we use but we primarily use QEMU GTK-UI w/ multi displays (QEMU with this params '-device virtio-vga,max_outputs=2,blob=true'). Thanks! > > -- > Best regards, > Dmitry
