Hi, Hsin-Yi:

On Thu, 2019-05-30 at 17:18 +0800, Hsin-Yi Wang wrote:

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.

Applied to mediatek-drm-fixes-5.2 [1], thanks.

[1] https://github.com/ckhu-mediatek/linux.git-tags/commits/mediatek-drm-fixes-5...

Regards, CK

Fixes: 0707632b5bac ("drm/mediatek: update DSI sub driver flow for sending commands to panel") Signed-off-by: Hsin-Yi Wang hsinyi@chromium.org

---

change log v3->v4:

• add comment in code.

---

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 b00eb2d2e086..730594a91440 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;