diff options
| author | John Keeping <john@metanate.com> | 2016-01-19 10:47:00 +0000 |
|---|---|---|
| committer | Mark Yao <mark.yao@rock-chips.com> | 2016-01-20 08:56:06 +0800 |
| commit | c9ad1d9946e849ac3d8821d91e136d7fd728dec5 (patch) | |
| tree | 55bdf59e04f94c426173e8fea79674c6c10596de /drivers/gpu | |
| parent | f2227f469782e55765deacb8ebcc7ec05fe04013 (diff) | |
drm/rockchip: explain why we can't wait_for_vblanks
Signed-off-by: John Keeping <john@metanate.com>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/rockchip/rockchip_drm_fb.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c index 87c77c4b5e50..3b8f652698f8 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c @@ -176,6 +176,21 @@ 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) { |