gfx: drv: Fix page flip lockup when requesting vblank fails

drm_vblank_get may fail if specified pipe is off. In that case we won't
get vblank even and can't call drm_vblank_put. But driver still has to
complete page flip to send required completion event to userspace.

Signed-off-by: Pauli Nieminen <pauli.nieminen@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

diff --git a/drivers/staging/mrst/drv/psb_page_flip.c b/drivers/staging/mrst/drv/psb_page_flip.c
index aa7a86a..4edd223 100644 (file)
--- a/drivers/staging/mrst/drv/psb_page_flip.c
+++ b/drivers/staging/mrst/drv/psb_page_flip.c
@@ -135,7 +135,8 @@ get_fb_meminfo(struct drm_framebuffer *fb)
 }
 
 static void
-psb_intel_flip_complete(struct pending_flip *pending_flip)
+psb_intel_flip_complete(struct pending_flip *pending_flip,
+               bool failed_vblank_get)
 {
        if (pending_flip) {
                struct drm_crtc *crtc = pending_flip->crtc;
@@ -144,7 +145,8 @@ psb_intel_flip_complete(struct pending_flip *pending_flip)
                int pipe = psb_intel_crtc->pipe;
 
                send_page_flip_event(dev, pipe, pending_flip);
-               drm_vblank_put(dev, pipe);
+               if (!failed_vblank_get)
+                       drm_vblank_put(dev, pipe);
                increase_read_ops_completed(pending_flip->old_mem_info);
                PVRSRVScheduleDeviceCallbacks();
 
@@ -160,7 +162,7 @@ psb_intel_crtc_process_vblank(struct drm_crtc *crtc)
 
        pending_flip = xchg(&psb_intel_crtc->pending_flip, NULL);
 
-       psb_intel_flip_complete(pending_flip);
+       psb_intel_flip_complete(pending_flip, false);
 }
 
 static void
@@ -174,11 +176,14 @@ sync_callback(struct pvr_pending_sync *pending_sync)
 
        write_scanout_regs(pending_flip, pending_flip->offset);
 
-       drm_vblank_get(dev, psb_intel_crtc->pipe);
+       if (drm_vblank_get(dev, psb_intel_crtc->pipe)) {
+               psb_intel_flip_complete(pending_flip, true);
+               pending_flip = NULL;
+       }
 
        pending_flip = xchg(&psb_intel_crtc->pending_flip, pending_flip);
 
-       psb_intel_flip_complete(pending_flip);
+       psb_intel_flip_complete(pending_flip, false);
 }
 
 int