mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(), which
needs ovl irq for drm_crtc_wait_one_vblank(), since after mtk_dsi_stop() is
called, ovl irq will be disabled. If drm_crtc_wait_one_vblank() is called
after last irq, it will timeout with this message: "vblank wait timed out
on crtc 0". This happens sometimes when turning off the screen.
In drm_atomic_helper.c#disable_outputs(),
the calling sequence when turning off the screen is:
1. mtk_dsi_encoder_disable()
--> mtk_output_dsi_disable()
--> mtk_dsi_stop(); /* sometimes make vblank timeout in
atomic_disable */
--> mtk_dsi_poweroff();
2. mtk_drm_crtc_atomic_disable()
--> drm_crtc_wait_one_vblank();
...
--> mtk_dsi_ddp_stop()
--> mtk_dsi_poweroff();
mtk_dsi_poweroff() has reference count design, change to make
mtk_dsi_stop() called in mtk_dsi_poweroff() when refcount is 0.
Fixes: 0707632b5b ("drm/mediatek: update DSI sub driver flow for sending commands to panel")
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Signed-off-by: CK Hu <ck.hu@mediatek.com>
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