staging: media: tegra-video: add syncpts for Tegra20 to struct tegra_vi

In preparation to implement Tegra20 parallel video capture, add a variable
to hold the required syncpt and document all the syncpt variables.
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/staging/media/tegra-video/vi.h

@@ -117,11 +117,13 @@ struct tegra_vi {
  * @vi: Tegra video input device structure
  * @frame_start_sp: host1x syncpoint pointer to synchronize programmed capture
  *		start condition with hardware frame start events through host1x
- *		syncpoint counters.
+ *		syncpoint counters. (Tegra210)
  * @mw_ack_sp: host1x syncpoint pointer to synchronize programmed memory write
  *		ack trigger condition with hardware memory write done at end of
- *		frame through host1x syncpoint counters.
+ *		frame through host1x syncpoint counters (On Tegra20 used for the
+ *              OUT_1 syncpt)
  * @sp_incr_lock: protects cpu syncpoint increment.
+ * @next_out_sp_idx: next expected value for mw_ack_sp[0], i.e. OUT_1 (Tegra20)
  *
  * @kthread_start_capture: kthread to start capture of single frame when
  *		vb buffer is available. This thread programs VI CSI hardware
@@ -175,6 +177,7 @@ struct tegra_vi_channel {
 	struct host1x_syncpt *mw_ack_sp[GANG_PORTS_MAX];
 	/* protects the cpu syncpoint increment */
 	spinlock_t sp_incr_lock[GANG_PORTS_MAX];
+	u32 next_out_sp_idx;
 
 	struct task_struct *kthread_start_capture;
 	wait_queue_head_t start_wait;