V4L/DVB (9726): cx18: Restore buffers that have fallen out of the transfer rotation

Restore buffers that have fallen out of the transfer rotation, and check
for coherent mailbox data when processing a stale mailbox.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 92 insertions, 27 deletions

diff --git a/drivers/media/video/cx18/cx18-driver.h b/drivers/media/video/cx18/cx18-driver.h
index cad352aeb837..f06290d32ecf 100644
--- a/drivers/media/video/cx18/cx18-driver.h
+++ b/drivers/media/video/cx18/cx18-driver.h
@@ -212,6 +212,7 @@ struct cx18_buffer {
         dma_addr_t dma_handle;
         u32 id;
         unsigned long b_flags;
+        unsigned skipped;
         char *buf;
 
         u32 bytesused;
diff --git a/drivers/media/video/cx18/cx18-mailbox.c b/drivers/media/video/cx18/cx18-mailbox.c
index e5d4f3112293..abd39aaa345c 100644
--- a/drivers/media/video/cx18/cx18-mailbox.c
+++ b/drivers/media/video/cx18/cx18-mailbox.c
@@ -120,7 +120,7 @@ static void dump_mb(struct cx18 *cx, struct cx18_mailbox *mb, char *name)
 
 static void epu_dma_done(struct cx18 *cx, struct cx18_epu_work_order *order)
 {
-        u32 handle, mdl_ack_count;
+        u32 handle, mdl_ack_count, id;
         struct cx18_mailbox *mb;
         struct cx18_mdl_ack *mdl_ack;
         struct cx18_stream *s;
@@ -133,19 +133,50 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_epu_work_order *order)
 
         if (s == NULL) {
                 CX18_WARN("Got DMA done notification for unknown/inactive"
-                          " handle %d\n", handle);
+                          " handle %d, %s mailbox seq no %d\n", handle,
+                          (order->flags & CX18_F_EWO_MB_STALE_UPON_RECEIPT) ?
+                          "stale" : "good", mb->request);
                 return;
         }
 
         mdl_ack_count = mb->args[2];
         mdl_ack = order->mdl_ack;
         for (i = 0; i < mdl_ack_count; i++, mdl_ack++) {
-                buf = cx18_queue_get_buf(s, mdl_ack->id, mdl_ack->data_used);
-                CX18_DEBUG_HI_DMA("DMA DONE for %s (buffer %d)\n", s->name,
-                                  mdl_ack->id);
+                id = mdl_ack->id;
+                /*
+                 * Simple integrity check for processing a stale (and possibly
+                 * inconsistent mailbox): make sure the buffer id is in the
+                 * valid range for the stream.
+                 *
+                 * We go through the trouble of dealing with stale mailboxes
+                 * because most of the time, the mailbox data is still valid and
+                 * unchanged (and in practice the firmware ping-pongs the
+                 * two mdl_ack buffers so mdl_acks are not stale).
+                 *
+                 * There are occasions when we get a half changed mailbox,
+                 * which this check catches for a handle & id mismatch.  If the
+                 * handle and id do correspond, the worst case is that we
+                 * completely lost the old buffer, but pick up the new buffer
+                 * early (but the new mdl_ack is guaranteed to be good in this
+                 * case as the firmware wouldn't point us to a new mdl_ack until
+                 * it's filled in).
+                 *
+                 * cx18_queue_get buf() will detect the lost buffers
+                 * and put them back in rotation eventually.
+                 */
+                if ((order->flags & CX18_F_EWO_MB_STALE_UPON_RECEIPT) &&
+                    !(id >= s->mdl_offset &&
+                      id < (s->mdl_offset + s->buffers))) {
+                        CX18_WARN("Fell behind! Ignoring stale mailbox with "
+                                  " inconsistent data. Lost buffer for mailbox "
+                                  "seq no %d\n", mb->request);
+                        break;
+                }
+                buf = cx18_queue_get_buf(s, id, mdl_ack->data_used);
+                CX18_DEBUG_HI_DMA("DMA DONE for %s (buffer %d)\n", s->name, id);
                 if (buf == NULL) {
                         CX18_WARN("Could not find buf %d for stream %s\n",
-                                  mdl_ack->id, s->name);
+                                  id, s->name);
                         continue;
                 }
 
@@ -158,6 +189,7 @@ static void epu_dma_done(struct cx18 *cx, struct cx18_epu_work_order *order)
                                          buf->bytesused);
 
                         cx18_buf_sync_for_device(s, buf);
+                        cx18_enqueue(s, buf, &s->q_free);
 
                         if (s->handle != CX18_INVALID_TASK_HANDLE &&
                             test_bit(CX18_F_S_STREAMING, &s->s_flags))
@@ -257,10 +289,10 @@ static void mb_ack_irq(struct cx18 *cx, struct cx18_epu_work_order *order)
         /* Don't ack if the RPU has gotten impatient and timed us out */
         if (req != cx18_readl(cx, &ack_mb->request) ||
             req == cx18_readl(cx, &ack_mb->ack)) {
-                CX18_WARN("Possibly falling behind: %s self-ack'ed our incoming"
-                          " %s to EPU mailbox (sequence no. %u) while "
-                          "processing\n",
-                          rpu_str[order->rpu], rpu_str[order->rpu], req);
+                CX18_DEBUG_WARN("Possibly falling behind: %s self-ack'ed our "
+                                "incoming %s to EPU mailbox (sequence no. %u) "
+                                "while processing\n",
+                                rpu_str[order->rpu], rpu_str[order->rpu], req);
                 order->flags |= CX18_F_EWO_MB_STALE_WHILE_PROC;
                 return;
         }
@@ -407,9 +439,10 @@ void cx18_api_epu_cmd_irq(struct cx18 *cx, int rpu)
                            2 * sizeof(u32));
 
         if (order_mb->request == order_mb->ack) {
-                CX18_WARN("Possibly falling behind: %s self-ack'ed our incoming"
-                          " %s to EPU mailbox (sequence no. %u)\n",
-                          rpu_str[rpu], rpu_str[rpu], order_mb->request);
+                CX18_DEBUG_WARN("Possibly falling behind: %s self-ack'ed our "
+                                "incoming %s to EPU mailbox (sequence no. %u)"
+                                "\n",
+                                rpu_str[rpu], rpu_str[rpu], order_mb->request);
                 dump_mb(cx, order_mb, "incoming");
                 order->flags = CX18_F_EWO_MB_STALE_UPON_RECEIPT;
         }
diff --git a/drivers/media/video/cx18/cx18-queue.c b/drivers/media/video/cx18/cx18-queue.c
index 5a3839403631..ff6df36328fd 100644
--- a/drivers/media/video/cx18/cx18-queue.c
+++ b/drivers/media/video/cx18/cx18-queue.c
@@ -49,6 +49,7 @@ void cx18_enqueue(struct cx18_stream *s, struct cx18_buffer *buf,
                 buf->bytesused = 0;
                 buf->readpos = 0;
                 buf->b_flags = 0;
+                buf->skipped = 0;
         }
         mutex_lock(&s->qlock);
         list_add_tail(&buf->list, &q->list);
@@ -67,6 +68,7 @@ struct cx18_buffer *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
                 list_del_init(q->list.next);
                 atomic_dec(&q->buffers);
                 q->bytesused -= buf->bytesused - buf->readpos;
+                buf->skipped = 0;
         }
         mutex_unlock(&s->qlock);
         return buf;
@@ -76,34 +78,63 @@ struct cx18_buffer *cx18_queue_get_buf(struct cx18_stream *s, u32 id,
         u32 bytesused)
 {
         struct cx18 *cx = s->cx;
-        struct list_head *p;
+        struct cx18_buffer *buf;
+        struct cx18_buffer *ret = NULL;
+        struct list_head *p, *t;
+        LIST_HEAD(r);
 
         mutex_lock(&s->qlock);
-        list_for_each(p, &s->q_free.list) {
-                struct cx18_buffer *buf =
-                        list_entry(p, struct cx18_buffer, list);
+        list_for_each_safe(p, t, &s->q_free.list) {
+                buf = list_entry(p, struct cx18_buffer, list);
 
                 if (buf->id != id) {
-                        CX18_DEBUG_HI_DMA("Skipping buffer %d searching for %d "
-                                          "in stream %s q_free\n", buf->id, id,
-                                          s->name);
+                        buf->skipped++;
+                        if (buf->skipped >= atomic_read(&s->q_free.buffers)-1) {
+                                /* buffer must have fallen out of rotation */
+                                atomic_dec(&s->q_free.buffers);
+                                list_move_tail(&buf->list, &r);
+                                CX18_WARN("Skipped %s, buffer %d, %d "
+                                          "times - it must have dropped out of "
+                                          "rotation\n", s->name, buf->id,
+                                          buf->skipped);
+                        }
                         continue;
                 }
 
                 buf->bytesused = bytesused;
-                if (s->type != CX18_ENC_STREAM_TYPE_TS) {
-                        atomic_dec(&s->q_free.buffers);
+                atomic_dec(&s->q_free.buffers);
+                if (s->type == CX18_ENC_STREAM_TYPE_TS) {
+                        /*
+                         * TS doesn't use q_full, but for sweeping up lost
+                         * buffers, we want the TS to requeue the buffer just
+                         * before sending the MDL back to the firmware, so we
+                         * pull it off the list here.
+                         */
+                        list_del_init(&buf->list);
+                } else {
                         atomic_inc(&s->q_full.buffers);
                         s->q_full.bytesused += buf->bytesused;
                         list_move_tail(&buf->list, &s->q_full.list);
                 }
 
-                mutex_unlock(&s->qlock);
-                return buf;
+                ret = buf;
+                break;
         }
         mutex_unlock(&s->qlock);
-        CX18_ERR("Cannot find buffer %d for stream %s\n", id, s->name);
-        return NULL;
+
+        /* Put lost buffers back into firmware transfer rotation */
+        while (!list_empty(&r)) {
+                buf = list_entry(r.next, struct cx18_buffer, list);
+                list_del_init(r.next);
+                cx18_enqueue(s, buf, &s->q_free);
+                cx18_vapi(cx, CX18_CPU_DE_SET_MDL, 5, s->handle,
+                       (void __iomem *)&cx->scb->cpu_mdl[buf->id] - cx->enc_mem,
+                       1, buf->id, s->buf_size);
+                CX18_INFO("Returning %s, buffer %d back to transfer rotation\n",
+                          s->name, buf->id);
+                /* and there was much rejoicing... */
+        }
+        return ret;
 }
 
 /* Move all buffers of a queue to q_free, while flushing the buffers */
@@ -118,7 +149,7 @@ static void cx18_queue_flush(struct cx18_stream *s, struct cx18_queue *q)
         while (!list_empty(&q->list)) {
                 buf = list_entry(q->list.next, struct cx18_buffer, list);
                 list_move_tail(q->list.next, &s->q_free.list);
-                buf->bytesused = buf->readpos = buf->b_flags = 0;
+                buf->bytesused = buf->readpos = buf->b_flags = buf->skipped = 0;
                 atomic_inc(&s->q_free.buffers);
         }
         cx18_queue_init(q);