disp: msm: sde: avoid race on in_clone_mode flag in wb encoder

The issue scenario is as follows:
1. User space issues CWB commit N-1, frame got picked up and wr_ptr_irq
   is received.

2. Next commit N CWB disable commit is programmed waits for N-1 wb_done
   irq.

3. The kickoff count is decremented on wb_done_irq of commit N-1
   and wb wait_for_idle is exited.

4. wb_frame_done irq thread execution stalled before populating fences
   and commit thread execution continues.

5. wb_reset disables in_clone_mode flag, the stalled wb_done_irq thread
   resumes its execution and signals the release fences on primary crtc.

6. Commit N-1  frame_done irq is received and release fences is
   signaled again.

Made changes to avoid the race between irq thread and commit thread
over in_clone_mode flag, by adding a lock over wb physical encoder.

Change-Id: Iba9b6613c49d413239c9603228fe16b0d64c0ab6
Signed-off-by: Andhavarapu Karthik <[email protected]>

msm/sde/sde_encoder_phys_wb.c

@@ -1814,11 +1814,13 @@ static void _sde_encoder_phys_wb_frame_done_helper(void *arg, bool frame_error)
 	struct sde_encoder_phys *phys_enc = &wb_enc->base;
 	u32 event = frame_error ? SDE_ENCODER_FRAME_EVENT_ERROR : 0;
 	u32 ubwc_error = 0;
+	unsigned long flags;
 
 	/* don't notify upper layer for internal commit */
 	if (phys_enc->enable_state == SDE_ENC_DISABLING && !phys_enc->in_clone_mode)
 		goto end;
 
+	spin_lock_irqsave(phys_enc->enc_spinlock, flags);
 	if (phys_enc->parent_ops.handle_frame_done &&
 			atomic_add_unless(&phys_enc->pending_kickoff_cnt, -1, 0)) {
 		event |= SDE_ENCODER_FRAME_EVENT_DONE;
@@ -1840,9 +1842,11 @@ static void _sde_encoder_phys_wb_frame_done_helper(void *arg, bool frame_error)
 					| SDE_ENCODER_FRAME_EVENT_SIGNAL_RETIRE_FENCE;
 		else
 			event |= SDE_ENCODER_FRAME_EVENT_SIGNAL_RELEASE_FENCE;
+	}
+	spin_unlock_irqrestore(phys_enc->enc_spinlock, flags);
 
+	if (event & SDE_ENCODER_FRAME_EVENT_DONE)
 		phys_enc->parent_ops.handle_frame_done(phys_enc->parent, phys_enc, event);
-	}
 
 	if (!phys_enc->in_clone_mode && phys_enc->parent_ops.handle_vblank_virt)
 		phys_enc->parent_ops.handle_vblank_virt(phys_enc->parent, phys_enc);
@@ -2251,12 +2255,15 @@ end:
 static int sde_encoder_phys_wb_wait_for_tx_complete(struct sde_encoder_phys *phys_enc)
 {
 	int rc = 0;
+	unsigned long flags;
 
 	if (atomic_read(&phys_enc->pending_kickoff_cnt))
 		rc = _sde_encoder_phys_wb_wait_for_idle(phys_enc, true);
 
 	if ((phys_enc->enable_state == SDE_ENC_DISABLING) && phys_enc->in_clone_mode) {
+		spin_lock_irqsave(phys_enc->enc_spinlock, flags);
 		_sde_encoder_phys_wb_reset_state(phys_enc);
+		spin_unlock_irqrestore(phys_enc->enc_spinlock, flags);
 		sde_encoder_phys_wb_irq_ctrl(phys_enc, false);
 	}