4.9-stable review patch. If anyone has any objections, please let me know.
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From: Lucas Stach l.stach@pengutronix.de
[ Upstream commit 6a055b92de15af987b4027826d43aa103c65a3c4 ]
Right now the vblank event completion is racing with the atomic update, which is especially bad when the PRE is in use, as one of the hardware issue workaround might extend the atomic commit for quite some time.
If the vblank IRQ happens to trigger during that time, we will prematurely signal the atomic commit completion to userspace, which causes tearing when userspace re-uses a framebuffer we haven't managed to flip away from yet.
Signed-off-by: Lucas Stach l.stach@pengutronix.de Signed-off-by: Philipp Zabel p.zabel@pengutronix.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/imx/ipuv3-crtc.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/drivers/gpu/drm/imx/ipuv3-crtc.c +++ b/drivers/gpu/drm/imx/ipuv3-crtc.c @@ -189,7 +189,11 @@ static void ipu_crtc_atomic_begin(struct struct drm_crtc_state *old_crtc_state) { drm_crtc_vblank_on(crtc); +}
+static void ipu_crtc_atomic_flush(struct drm_crtc *crtc, + struct drm_crtc_state *old_crtc_state) +{ spin_lock_irq(&crtc->dev->event_lock); if (crtc->state->event) { WARN_ON(drm_crtc_vblank_get(crtc)); @@ -257,6 +261,7 @@ static const struct drm_crtc_helper_func .mode_set_nofb = ipu_crtc_mode_set_nofb, .atomic_check = ipu_crtc_atomic_check, .atomic_begin = ipu_crtc_atomic_begin, + .atomic_flush = ipu_crtc_atomic_flush, .atomic_disable = ipu_crtc_atomic_disable, .enable = ipu_crtc_enable, };