Signed-off-by: John Keeping john@metanate.com --- v2: - Add more detail of the particular race that could happen if we used drm_atomic_helper_wait_for_vblanks().
drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c index 679d23a..cf0b7bd 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c @@ -177,6 +177,21 @@ static void rockchip_crtc_wait_for_update(struct drm_crtc *crtc) crtc_funcs->wait_for_update(crtc); }
+/* + * We can't use drm_atomic_helper_wait_for_vblanks() because rk3288 and rk3066 + * have hardware counters for neither vblanks nor scanlines, which results in + * a race where: + * | <-- HW vsync irq and reg take effect + * plane_commit --> | + * get_vblank and wait --> | + * | <-- handle_vblank, vblank->count + 1 + * cleanup_fb --> | + * iommu crash --> | + * | <-- HW vsync irq and reg take effect + * + * This function is equivalent but uses rockchip_crtc_wait_for_update() instead + * of waiting for vblank_count to change. + */ static void rockchip_atomic_wait_for_complete(struct drm_device *dev, struct drm_atomic_state *old_state) {