After disabling and reenabling the CRTC the DCU sometimes got stuck displaying the whole screen with a solid color. Disabling and reenabling the CRTC did not recover from the situation. This was often reproducable by just restarting the X-Server.

The disabling sequence is not explicitly documented. But it turns out that disabling the planes before disabling the CRTC seems to prevent the above situation from happening.

Use the callback ->atomic_disable instead of ->disable which allows to use the drm_atomic_helper_disable_planes_on_crtc() helper to disable planes before disabling the controller.

Signed-off-by: Stefan Agner stefan@agner.ch --- drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c index 2ea9dbd..deb5743 100644 --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_crtc.c @@ -44,11 +44,15 @@ static void fsl_dcu_drm_crtc_atomic_flush(struct drm_crtc *crtc, } }

-static void fsl_dcu_drm_disable_crtc(struct drm_crtc *crtc) +static void fsl_dcu_drm_crtc_atomic_disable(struct drm_crtc *crtc, + struct drm_crtc_state *old_crtc_state) { struct drm_device *dev = crtc->dev; struct fsl_dcu_drm_device *fsl_dev = dev->dev_private;

+ /* always disable planes on the CRTC */ + drm_atomic_helper_disable_planes_on_crtc(old_crtc_state, true); + drm_crtc_vblank_off(crtc);

regmap_update_bits(fsl_dev->regmap, DCU_DCU_MODE, @@ -127,8 +131,8 @@ static void fsl_dcu_drm_crtc_mode_set_nofb(struct drm_crtc *crtc) }

static const struct drm_crtc_helper_funcs fsl_dcu_drm_crtc_helper_funcs = { + .atomic_disable = fsl_dcu_drm_crtc_atomic_disable, .atomic_flush = fsl_dcu_drm_crtc_atomic_flush, - .disable = fsl_dcu_drm_disable_crtc, .enable = fsl_dcu_drm_crtc_enable, .mode_set_nofb = fsl_dcu_drm_crtc_mode_set_nofb, };