Re: [PATCH] drm/stm: ltdc: check crtc state before enabling LIE

Following investigations of a hardware bug, the LIE interrupt
can occur while the display controller is not activated.
LIE interrupt (vblank) don't have to be set if the CRTC is not
enabled.

Signed-off-by: Yannick Fertre <redacted>
---
  drivers/gpu/drm/stm/ltdc.c | 7 ++++++-
  1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
index c2815e8..ea654c7 100644
--- a/drivers/gpu/drm/stm/ltdc.c
+++ b/drivers/gpu/drm/stm/ltdc.c

@@ -648,9 +648,14 @@ static const struct drm_crtc_helper_funcs ltdc_crtc_helper_funcs = {
  static int ltdc_crtc_enable_vblank(struct drm_crtc *crtc)
  {
  	struct ltdc_device *ldev = crtc_to_ltdc(crtc);
+	struct drm_crtc_state *state = crtc->state;
  
  	DRM_DEBUG_DRIVER("\n");
-	reg_set(ldev->regs, LTDC_IER, IER_LIE);
+
+	if (state->enable)
+		reg_set(ldev->regs, LTDC_IER, IER_LIE);
+	else
+		return -EPERM;
  
  	return 0;
  }