3 files changed, 33 insertions, 1 deletions

diff --git a/drivers/media/video/cx18/cx18-mailbox.c b/drivers/media/video/cx18/cx18-mailbox.c
index f231dd09c720..0ac0e2c993a5 100644
--- a/drivers/media/video/cx18/cx18-mailbox.c
+++ b/drivers/media/video/cx18/cx18-mailbox.c
@@ -223,8 +223,11 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_in_work_order *order)
                 CX18_DEBUG_HI_DMA("%s recv bytesused = %d\n",
                                   s->name, mdl->bytesused);
 
-                if (s->type != CX18_ENC_STREAM_TYPE_TS)
+                if (s->type != CX18_ENC_STREAM_TYPE_TS) {
                         cx18_enqueue(s, mdl, &s->q_full);
+                        if (s->type == CX18_ENC_STREAM_TYPE_IDX)
+                                cx18_stream_rotate_idx_mdls(cx);
+                }
                 else {
                         cx18_mdl_send_to_dvb(s, mdl);
                         cx18_enqueue(s, mdl, &s->q_free);
diff --git a/drivers/media/video/cx18/cx18-streams.c b/drivers/media/video/cx18/cx18-streams.c
index 9755f4416e96..680e7da5e5e4 100644
--- a/drivers/media/video/cx18/cx18-streams.c
+++ b/drivers/media/video/cx18/cx18-streams.c
@@ -463,6 +463,32 @@ static void cx18_vbi_setup(struct cx18_stream *s)
         cx18_api(cx, CX18_CPU_SET_RAW_VBI_PARAM, 6, data);
 }
 
+void cx18_stream_rotate_idx_mdls(struct cx18 *cx)
+{
+        struct cx18_stream *s = &cx->streams[CX18_ENC_STREAM_TYPE_IDX];
+        struct cx18_mdl *mdl;
+
+        if (!cx18_stream_enabled(s))
+                return;
+
+        /* Return if the firmware is not running low on MDLs */
+        if ((atomic_read(&s->q_free.depth) + atomic_read(&s->q_busy.depth)) >=
+                                            CX18_ENC_STREAM_TYPE_IDX_FW_MDL_MIN)
+                return;
+
+        /* Return if there are no MDLs to rotate back to the firmware */
+        if (atomic_read(&s->q_full.depth) < 2)
+                return;
+
+        /*
+         * Take the oldest IDX MDL still holding data, and discard its index
+         * entries by scheduling the MDL to go back to the firmware
+         */
+        mdl = cx18_dequeue(s, &s->q_full);
+        if (mdl != NULL)
+                cx18_enqueue(s, mdl, &s->q_free);
+}
+
 static
 struct cx18_queue *_cx18_stream_put_mdl_fw(struct cx18_stream *s,
                                            struct cx18_mdl *mdl)
diff --git a/drivers/media/video/cx18/cx18-streams.h b/drivers/media/video/cx18/cx18-streams.h
index 7b36225c4abe..0bff0fa29763 100644
--- a/drivers/media/video/cx18/cx18-streams.h
+++ b/drivers/media/video/cx18/cx18-streams.h
@@ -28,6 +28,9 @@ int cx18_streams_setup(struct cx18 *cx);
 int cx18_streams_register(struct cx18 *cx);
 void cx18_streams_cleanup(struct cx18 *cx, int unregister);
 
+#define CX18_ENC_STREAM_TYPE_IDX_FW_MDL_MIN (3)
+void cx18_stream_rotate_idx_mdls(struct cx18 *cx);
+
 static inline bool cx18_stream_enabled(struct cx18_stream *s)
 {
         return s->video_dev || s->dvb.enabled ||