[PATCH 4/5] media: hws: harden video DMA queue ownership

[Ben Hoff]

---
 drivers/media/pci/hws/hws_video.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/media/pci/hws/hws_video.c b/drivers/media/pci/hws/hws_video.c
index 3a7b2abda502..58bcc2e7030d 100644
--- a/drivers/media/pci/hws/hws_video.c
+++ b/drivers/media/pci/hws/hws_video.c
@@ -330,8 +330,8 @@ static bool hws_force_no_signal_frame(struct hws_video *v, const char *tag)
 	struct hws_pcie_dev *hws;
 	unsigned long flags;
 	struct hwsvideo_buffer *buf = NULL, *next = NULL;
-	bool have_next = false;
 	bool programmed = false;
+	int ret = 0;
 
 	if (!v)
 		return false;
@@ -354,22 +354,31 @@ static bool hws_force_no_signal_frame(struct hws_video *v, const char *tag)
 	if (v->next_prepared) {
 		next = v->next_prepared;
 		v->next_prepared = NULL;
-		next->slot = HWS_VIDEO_DIRECT_SLOT;
 		v->active = next;
-		have_next = true;
+		programmed = true;
 	} else if (!list_empty(&v->capture_queue)) {
 		next = list_first_entry(&v->capture_queue,
 					struct hwsvideo_buffer, list);
 		list_del_init(&next->list);
 		if (v->queued_count)
 			v->queued_count--;
-		next->slot = HWS_VIDEO_DIRECT_SLOT;
-		v->active = next;
-		have_next = true;
+		ret = hws_program_dma_for_buffer(hws, v->channel_index, next);
+		if (ret) {
+			list_add(&next->list, &v->capture_queue);
+			v->queued_count++;
+			next = NULL;
+		} else {
+			v->active = next;
+			programmed = true;
+		}
 	} else {
 		v->active = NULL;
 	}
 	spin_unlock_irqrestore(&v->irq_lock, flags);
+	if (ret)
+		dev_warn_ratelimited(&hws->pdev->dev,
+				     "%s: failed to arm no-signal buffer ch=%u ret=%d\n",
+				     tag, v->channel_index, ret);
 	if (!buf)
 		return false;
 	/* Complete buffer with a neutral frame so dequeuers keep running. */
@@ -385,10 +394,6 @@ static bool hws_force_no_signal_frame(struct hws_video *v, const char *tag)
 		vb2v->vb2_buf.timestamp = ktime_get_ns();
 		vb2_buffer_done(&vb2v->vb2_buf, VB2_BUF_STATE_DONE);
 	}
-	if (have_next && next) {
-		if (!hws_program_dma_for_buffer(hws, v->channel_index, next))
-			programmed = true;
-	}
 	if (programmed) {
 		wmb(); /* ensure descriptors visible before enabling capture */
 		hws_enable_video_capture(hws, v->channel_index, true);
-- 
2.54.0