[media] omap3isp: ccdc: Fix freeze when a short frame is received

In BT.656 mode the synchronization signals are generated by the CCDC
from the embedded sync codes. The VD0 and VD1 interrupts are thus only
triggered when the CCDC is enabled, unlike external sync mode where the
line counter runs even when the CCDC is stopped. We can't disable the
CCDC at VD1 time, as no VD0 interrupt would be generated for a short
frame, which would result in the CCDC being stopped and no VD interrupt
generated anymore. The CCDC is stopped from the VD0 interrupt handler
instead for BT.656.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Enrico Butera <ebutera@users.sourceforge.net>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/platform/omap3isp/ispccdc.c

@@ -1647,10 +1647,27 @@ static void ccdc_vd0_isr(struct isp_ccdc_device *ccdc)
 		atomic_inc(&pipe->frame_number);
 	}
 
+	/* Emulate a VD1 interrupt for BT.656 mode, as we can't stop the CCDC in
+	 * the VD1 interrupt handler in that mode without risking a CCDC stall
+	 * if a short frame is received.
+	 */
+	if (ccdc->bt656) {
+		spin_lock_irqsave(&ccdc->lock, flags);
+		if (ccdc->state == ISP_PIPELINE_STREAM_CONTINUOUS &&
+		    ccdc->output & CCDC_OUTPUT_MEMORY) {
+			if (ccdc->lsc.state != LSC_STATE_STOPPED)
+				__ccdc_lsc_enable(ccdc, 0);
+			__ccdc_enable(ccdc, 0);
+		}
+		ccdc_handle_stopping(ccdc, CCDC_EVENT_VD1);
+		spin_unlock_irqrestore(&ccdc->lock, flags);
+	}
+
 	if (ccdc->output & CCDC_OUTPUT_MEMORY)
 		restart = ccdc_isr_buffer(ccdc);
 
 	spin_lock_irqsave(&ccdc->lock, flags);
+
 	if (ccdc_handle_stopping(ccdc, CCDC_EVENT_VD0)) {
 		spin_unlock_irqrestore(&ccdc->lock, flags);
 		return;
@@ -1672,6 +1689,18 @@ static void ccdc_vd1_isr(struct isp_ccdc_device *ccdc)
 {
 	unsigned long flags;
 
+	/* In BT.656 mode the synchronization signals are generated by the CCDC
+	 * from the embedded sync codes. The VD0 and VD1 interrupts are thus
+	 * only triggered when the CCDC is enabled, unlike external sync mode
+	 * where the line counter runs even when the CCDC is stopped. We can't
+	 * disable the CCDC at VD1 time, as no VD0 interrupt would be generated
+	 * for a short frame, which would result in the CCDC being stopped and
+	 * no VD interrupt generated anymore. The CCDC is stopped from the VD0
+	 * interrupt handler instead for BT.656.
+	 */
+	if (ccdc->bt656)
+		return;
+
 	spin_lock_irqsave(&ccdc->lsc.req_lock, flags);
 
 	/*