drm/amd/display: Send vblank and user events at vsartup for DCN

[Why]

For DCN hardware, the crtc_high_irq handler is assigned to the vstartup
interrupt. This is different from DCE, which has it assigned to vblank
start.

We'd like to send vblank and user events at vstartup because:

* It happens close enough to vupdate - the point of no return for HW.

* It is programmed as lines relative to vblank end - i.e. it is not in
  the variable portion when VRR is enabled. We should signal user
  events here.

* The pflip interrupt responsible for sending user events today only
  fires if the DCH HUBP component is not clock gated. In situations
  where planes are disabled - but the CRTC is enabled - user events won't
  be sent out, leading to flip done timeouts.

Consequently, this makes vupdate on DCN hardware redundant. It will be
removed in the next change.

[How]

Add a DCN-specific crtc_high_irq handler, and hook it to the VStartup
signal. Inside the DCN handler, we send off user events if the pflip
handler hasn't already done so.

Reviewed-by: Nicholas Kazlauskas <[email protected]>
Signed-off-by: Leo Li <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -485,6 +485,69 @@ static void dm_crtc_high_irq(void *interrupt_params)
 	}
 }
 
+
+/**
+ * dm_dcn_crtc_high_irq() - Handles VStartup interrupt for DCN generation ASICs
+ * @interrupt params - interrupt parameters
+ *
+ * Notify DRM's vblank event handler at VSTARTUP
+ *
+ * Unlike DCE hardware, we trigger the handler at VSTARTUP. at which:
+ * * We are close enough to VUPDATE - the point of no return for hw
+ * * We are in the fixed portion of variable front porch when vrr is enabled
+ * * We are before VUPDATE, where double-buffered vrr registers are swapped
+ *
+ * It is therefore the correct place to signal vblank, send user flip events,
+ * and update VRR.
+ */
+static void dm_dcn_crtc_high_irq(void *interrupt_params)
+{
+	struct common_irq_params *irq_params = interrupt_params;
+	struct amdgpu_device *adev = irq_params->adev;
+	struct amdgpu_crtc *acrtc;
+	struct dm_crtc_state *acrtc_state;
+	unsigned long flags;
+
+	acrtc = get_crtc_by_otg_inst(adev, irq_params->irq_src - IRQ_TYPE_VBLANK);
+
+	if (!acrtc)
+		return;
+
+	acrtc_state = to_dm_crtc_state(acrtc->base.state);
+
+	DRM_DEBUG_DRIVER("crtc:%d, vupdate-vrr:%d\n", acrtc->crtc_id,
+				amdgpu_dm_vrr_active(acrtc_state));
+
+	amdgpu_dm_crtc_handle_crc_irq(&acrtc->base);
+	drm_crtc_handle_vblank(&acrtc->base);
+
+	spin_lock_irqsave(&adev->ddev->event_lock, flags);
+
+	if (acrtc_state->vrr_params.supported &&
+	    acrtc_state->freesync_config.state == VRR_STATE_ACTIVE_VARIABLE) {
+		mod_freesync_handle_v_update(
+		adev->dm.freesync_module,
+		acrtc_state->stream,
+		&acrtc_state->vrr_params);
+
+		dc_stream_adjust_vmin_vmax(
+			adev->dm.dc,
+			acrtc_state->stream,
+			&acrtc_state->vrr_params.adjust);
+	}
+
+	if (acrtc->pflip_status == AMDGPU_FLIP_SUBMITTED) {
+		if (acrtc->event) {
+			drm_crtc_send_vblank_event(&acrtc->base, acrtc->event);
+			acrtc->event = NULL;
+			drm_crtc_vblank_put(&acrtc->base);
+		}
+		acrtc->pflip_status = AMDGPU_FLIP_NONE;
+	}
+
+	spin_unlock_irqrestore(&adev->ddev->event_lock, flags);
+}
+
 static int dm_set_clockgating_state(void *handle,
 		  enum amd_clockgating_state state)
 {
@@ -2175,7 +2238,7 @@ static int dcn10_register_irq_handlers(struct amdgpu_device *adev)
 		c_irq_params->irq_src = int_params.irq_source;
 
 		amdgpu_dm_irq_register_interrupt(adev, &int_params,
-				dm_crtc_high_irq, c_irq_params);
+				dm_dcn_crtc_high_irq, c_irq_params);
 	}
 
 	/* Use VUPDATE_NO_LOCK interrupt on DCN, which seems to correspond to