[Xen-devel] [PATCH v4 15/15] drm/xen: Explicitly disable automatic sending of vblank event

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

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@xxxxxxx>
Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
 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;
+
+       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


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