drm/mediatek: call mtk_dsi_stop() after mtk_drm_crtc_atomic_disable()

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: 0707632b5bac ("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>

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 1ae3be99e0ffed255ac27d4c27506c908e82e84f..179f2b080342a6b7ca7b5c1477ee1cf8cebb7291 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -630,6 +630,15 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
        if (--dsi->refcount != 0)
                return;
 
+       /*
+        * mtk_dsi_stop() and mtk_dsi_start() is asymmetric, since
+        * mtk_dsi_stop() should be called after mtk_drm_crtc_atomic_disable(),
+        * which needs irq for vblank, and mtk_dsi_stop() will disable irq.
+        * mtk_dsi_start() needs to be called in mtk_output_dsi_enable(),
+        * after dsi is fully set.
+        */
+       mtk_dsi_stop(dsi);
+
        if (!mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500)) {
                if (dsi->panel) {
                        if (drm_panel_unprepare(dsi->panel)) {
@@ -696,7 +705,6 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
                }
        }
 
-       mtk_dsi_stop(dsi);
        mtk_dsi_poweroff(dsi);
 
        dsi->enabled = false;