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Subject[PATCH AUTOSEL 5.1 19/51] drm/mediatek: call mtk_dsi_stop() after mtk_drm_crtc_atomic_disable()
Date
From: Hsin-Yi Wang <hsinyi@chromium.org>

[ Upstream commit 2458d9d6d94be982b917e93c61a89b4426f32e31 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/mediatek/mtk_dsi.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 1ae3be99e0ff..179f2b080342 100644
--- 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;
--
2.20.1
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