[PATCH] drm/msm: dpu: Don't enable vblank interrupts in irq_control

[Sean Paul <sean@poorly.run>]

From: Sean Paul <seanpaul@chromium.org>

The irq_control function is called upon encoder enable/disable and turns
on/off the vblank interrupts. Unfortunately, it enables them when the
drm code is not expecting them to be on. As a result, we can get into
nasty locking situations.

vblank interrupts should be solely managed by the drm core via
control_vblank_irq(). This patch removes the vblank irq handling from
irq_control.

Here's some tracing before this patch:
-- CRTC is enabled, irq_control is called, drm_vblank reference is 0
   25.078455: dpu_crtc_enable: id:46 enable:true state{enabled:false}
-- vblank irqs incorrectly firing, drm_crtc_handle_vblank is called from them
   25.290067: dpu_crtc_vblank_cb: id=46
   25.306691: dpu_crtc_vblank_cb: id=46
-- drm core enables vblank interrupts, drm_vblank_reference > 0
   25.311527: dpu_crtc_vblank: id:46 enable:true state{enabled:true}
-- vblank irqs continue (correctly)
   25.323351: dpu_crtc_vblank_cb: id=46
   25.340033: dpu_crtc_vblank_cb: id=46
   25.356701: dpu_crtc_vblank_cb: id=46

And after this patch:
-- CRTC is enabled, irq_control does not enable vblank interrupts
  123.861353: dpu_crtc_enable: id:46 enable:true state{enabled:false}
-- drm core enables vblank, we enable the irq
  124.192916: dpu_crtc_vblank: id:46 enable:true state{enabled:true}
-- vblank irqs start at the correct time
  124.200548: dpu_crtc_vblank_cb: id=46
  124.217195: dpu_crtc_vblank_cb: id=46
  124.233848: dpu_crtc_vblank_cb: id=46

Signed-off-by: Sean Paul <seanpaul@chromium.org>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c | 2 --
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 6 ------
 2 files changed, 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
index 99ab5ca9bed3..c9eaa3516e9a 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
@@ -339,7 +339,6 @@ static void dpu_encoder_phys_cmd_irq_control(struct dpu_encoder_phys *phys_enc,
 	if (enable) {
 		dpu_encoder_helper_register_irq(phys_enc, INTR_IDX_PINGPONG);
 		dpu_encoder_helper_register_irq(phys_enc, INTR_IDX_UNDERRUN);
-		dpu_encoder_phys_cmd_control_vblank_irq(phys_enc, true);
 
 		if (dpu_encoder_phys_cmd_is_master(phys_enc))
 			dpu_encoder_helper_register_irq(phys_enc,
@@ -350,7 +349,6 @@ static void dpu_encoder_phys_cmd_irq_control(struct dpu_encoder_phys *phys_enc,
 					INTR_IDX_CTL_START);
 
 		dpu_encoder_helper_unregister_irq(phys_enc, INTR_IDX_UNDERRUN);
-		dpu_encoder_phys_cmd_control_vblank_irq(phys_enc, false);
 		dpu_encoder_helper_unregister_irq(phys_enc, INTR_IDX_PINGPONG);
 	}
 }
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index acdab5b0db18..e3125a1ab3dc 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -706,7 +706,6 @@ static void dpu_encoder_phys_vid_irq_control(struct dpu_encoder_phys *phys_enc,
 		bool enable)
 {
 	struct dpu_encoder_phys_vid *vid_enc;
-	int ret;
 
 	if (!phys_enc)
 		return;
@@ -719,13 +718,8 @@ static void dpu_encoder_phys_vid_irq_control(struct dpu_encoder_phys *phys_enc,
 			    atomic_read(&phys_enc->vblank_refcount));
 
 	if (enable) {
-		ret = dpu_encoder_phys_vid_control_vblank_irq(phys_enc, true);
-		if (ret)
-			return;
-
 		dpu_encoder_helper_register_irq(phys_enc, INTR_IDX_UNDERRUN);
 	} else {
-		dpu_encoder_phys_vid_control_vblank_irq(phys_enc, false);
 		dpu_encoder_helper_unregister_irq(phys_enc, INTR_IDX_UNDERRUN);
 	}
 }
-- 
Sean Paul, Software Engineer, Google / Chromium OS

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