On Thu, Jan 23, 2020 at 10:21:23AM +0100, Thomas Zimmermann wrote:
The atomic helpers automatically send out fake VBLANK events if no vblanking has been initialized. This would apply to xen, but xen has its own vblank logic. To avoid interfering with the atomic helpers, disable automatic vblank events explictly.
v4:
- separate commit from core vblank changes
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Acked-by: Gerd Hoffmann kraxel@redhat.com
On all the driver patches:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
drivers/gpu/drm/xen/xen_drm_front_kms.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/drivers/gpu/drm/xen/xen_drm_front_kms.c b/drivers/gpu/drm/xen/xen_drm_front_kms.c index 4f34c5208180..efde4561836f 100644 --- a/drivers/gpu/drm/xen/xen_drm_front_kms.c +++ b/drivers/gpu/drm/xen/xen_drm_front_kms.c @@ -220,6 +220,18 @@ static bool display_send_page_flip(struct drm_simple_display_pipe *pipe, return false; }
+static int display_check(struct drm_simple_display_pipe *pipe,
struct drm_plane_state *plane_state,struct drm_crtc_state *crtc_state)+{
- /* Make sure that DRM helpers don't send VBLANK events
* automatically. Xen has it's own logic to do so.*/- crtc_state->no_vblank = false;
So this here is strictly speaking dead code, because the fake_vblank helper makes sure to only send out the event if it hasn't been processed yet.
Which is a bit awkward, since it does this silently, potentially hiding bugs. We already have a warning that complains if a crtc_state->event hasn't been processed at all. But with the auto-vblank stuff here we kinda defeat that a bit ... I think adding a WARN_ON in fake_vblank that fires if no_vblank is set, but the event is somehow gone, would be really useful. That would point at some serious driver snafu ...
Care to throw that on top? -Daniel
- return 0;
+}
static void display_update(struct drm_simple_display_pipe *pipe, struct drm_plane_state *old_plane_state) { @@ -284,6 +296,7 @@ static const struct drm_simple_display_pipe_funcs display_funcs = { .enable = display_enable, .disable = display_disable, .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
- .check = display_check, .update = display_update,
};
-- 2.24.1