[PATCH v5 2/2] drm/mediatek: Fix iommu fault during crtc enabling

[Jason-JH.Lin]

The difference between drm_atomic_helper_commit_tail() and
drm_atomic_helper_commit_tail_rpm() is
drm_atomic_helper_commit_tail() will commit plane first and
then enable crtc, drm_atomic_helper_commit_tail_rpm() will
enable crtc first and then commit plane.

Before mediatek-drm enables crtc, the power and clk required
by OVL have not been turned on, so the commit plane cannot be
committed before crtc is enabled. That means OVL layer should
not be enabled before crtc is enabled.
Therefore, the atomic_commit_tail of mediatek-drm is hooked with
drm_atomic_helper_commit_tail_rpm().

Another reason is that the plane_state of drm_atomic_state is not
synchronized with the plane_state stored in mtk_crtc during crtc enablng,
so just set all planes to disabled.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
Signed-off-by: Jason-JH.Lin <jason-jh.lin at mediatek.com>
Reviewed-by: Alexandre Mergnat <amergnat at baylibre.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index d40142842f85..51d10e65004e 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -410,6 +410,9 @@ static int mtk_crtc_ddp_hw_init(struct mtk_drm_crtc *mtk_crtc)
 		unsigned int local_layer;
 
 		plane_state = to_mtk_plane_state(plane->state);
+
+		/* should not enable layer before crtc enabled */
+		plane_state->pending.enable = false;
 		comp = mtk_drm_ddp_comp_for_plane(crtc, plane, &local_layer);
 		if (comp)
 			mtk_ddp_comp_layer_config(comp, local_layer,
-- 
2.18.0