On Tue, Aug 18, 2020 at 09:25:10AM +0200, Gerd Hoffmann wrote:
> When going through a disable/enable cycle without changing the
> framebuffer the optimization added by commit 3954ff10e06e ("drm/virtio:
> skip set_scanout if framebuffer didn't change") causes the screen stay
> blank. Add a bool to force an update to fix that.
>
> v2: use drm_atomic_crtc_needs_modeset() (Daniel).
>
> Cc: 1882851@xxxxxxxxxxxxxxxxxx
> Fixes: 3954ff10e06e ("drm/virtio: skip set_scanout if framebuffer didn't change")
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> drivers/gpu/drm/virtio/virtgpu_drv.h | 1 +
> drivers/gpu/drm/virtio/virtgpu_display.c | 11 +++++++++++
> drivers/gpu/drm/virtio/virtgpu_plane.c | 4 +++-
> 3 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 9ff9f4ac0522..4ab1b0ba2925 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -138,6 +138,7 @@ struct virtio_gpu_output {
> int cur_x;
> int cur_y;
> bool enabled;
> + bool needs_modeset;
Maybe for a follow-up in -next: The clean atomic way of doing this is to
put this into a virtio_crtc_state, compute it in atomic_check, and then
fish it out (through old_state->state lookup, somewhat contrived I know)
in the commit side. Putting random atomic commit state tracking stuff into
non-state structures without appropriate amounts of locks is kinda iffy
and means more work for reviewers pondering whether it all works
correctly.
Cheers, Daniel
> };
> #define drm_crtc_to_virtio_gpu_output(x) \
> container_of(x, struct virtio_gpu_output, crtc)
> diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
> index 2c2742b8d657..6c26b41f4e0d 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_display.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_display.c
> @@ -123,6 +123,17 @@ static int virtio_gpu_crtc_atomic_check(struct drm_crtc *crtc,
> static void virtio_gpu_crtc_atomic_flush(struct drm_crtc *crtc,
> struct drm_crtc_state *old_state)
> {
> + struct virtio_gpu_output *output = drm_crtc_to_virtio_gpu_output(crtc);
> +
> + /*
> + * virtio-gpu can't do modeset and plane update operations
> + * independant from each other. So the actual modeset happens
> + * in the plane update callback, and here we just check
> + * whenever we must force the modeset.
> + */
> + if (drm_atomic_crtc_needs_modeset(crtc->state)) {
> + output->needs_modeset = true;
> + }
> }
>
> static const struct drm_crtc_helper_funcs virtio_gpu_crtc_helper_funcs = {
> diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
> index 52d24179bcec..65757409d9ed 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_plane.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
> @@ -163,7 +163,9 @@ static void virtio_gpu_primary_plane_update(struct drm_plane *plane,
> plane->state->src_w != old_state->src_w ||
> plane->state->src_h != old_state->src_h ||
> plane->state->src_x != old_state->src_x ||
> - plane->state->src_y != old_state->src_y) {
> + plane->state->src_y != old_state->src_y ||
> + output->needs_modeset) {
> + output->needs_modeset = false;
> DRM_DEBUG("handle 0x%x, crtc %dx%d+%d+%d, src %dx%d+%d+%d\n",
> bo->hw_res_handle,
> plane->state->crtc_w, plane->state->crtc_h,
> --
> 2.18.4
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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