From: Maxime Jourdan <[email protected]>

- Redo the logic where VP9 gets fresh CAPTURE buffers. The previous code
  could lead to a hardlock.
- Reserve 4 margin buffers instead of 3, as apparently there are corner
  cases where 3 is not enough.

Fixes: e9a3eb4819ca ("media: meson: vdec: add VP9 input support")
Fixes: 00c43088aa68 ("media: meson: vdec: add VP9 decoder support")
Signed-off-by: Maxime Jourdan <[email protected]>
Signed-off-by: Neil Armstrong <[email protected]>
---
 drivers/staging/media/meson/vdec/codec_vp9.c | 41 +++++++++++++-------
 drivers/staging/media/meson/vdec/esparser.c  | 24 ++++++------
 2 files changed, 38 insertions(+), 27 deletions(-)

diff --git a/drivers/staging/media/meson/vdec/codec_vp9.c 
b/drivers/staging/media/meson/vdec/codec_vp9.c
index 897f5d7a6aad..28a7e62e7371 100644
--- a/drivers/staging/media/meson/vdec/codec_vp9.c
+++ b/drivers/staging/media/meson/vdec/codec_vp9.c
@@ -1185,6 +1185,29 @@ static void codec_vp9_set_mc(struct amvdec_session *sess,
        amvdec_write_dos(core, VP9D_MPP_REF_SCALE_ENBL, scale);
 }
 
+/*
+ * Get a free VB2 buffer that isn't currently used.
+ * VP9 references are held sometimes for so long that it's not really an option
+ * to hold them until they're no longer referenced, as it would delay the
+ * CAPTURE queue too much
+ */
+static struct vb2_v4l2_buffer *get_free_vbuf(struct amvdec_session *sess)
+{
+       struct codec_vp9 *vp9 = sess->priv;
+       struct vb2_v4l2_buffer *vbuf = v4l2_m2m_dst_buf_remove(sess->m2m_ctx);
+       struct vb2_v4l2_buffer *vbuf2;
+
+       if (!vbuf)
+               return NULL;
+
+       if (!codec_vp9_get_frame_by_idx(vp9, vbuf->vb2_buf.index))
+               return vbuf;
+
+       vbuf2 = get_free_vbuf(sess);
+       v4l2_m2m_buf_queue(sess->m2m_ctx, vbuf);
+       return vbuf2;
+}
+
 static struct vp9_frame *codec_vp9_get_new_frame(struct amvdec_session *sess)
 {
        struct codec_vp9 *vp9 = sess->priv;
@@ -1196,25 +1219,13 @@ static struct vp9_frame *codec_vp9_get_new_frame(struct 
amvdec_session *sess)
        if (!new_frame)
                return NULL;
 
-       vbuf = v4l2_m2m_dst_buf_remove(sess->m2m_ctx);
+       vbuf = get_free_vbuf(sess);
        if (!vbuf) {
                dev_err(sess->core->dev, "No dst buffer available\n");
                kfree(new_frame);
                return NULL;
        }
 
-       while (codec_vp9_get_frame_by_idx(vp9, vbuf->vb2_buf.index)) {
-               struct vb2_v4l2_buffer *old_vbuf = vbuf;
-
-               vbuf = v4l2_m2m_dst_buf_remove(sess->m2m_ctx);
-               v4l2_m2m_buf_queue(sess->m2m_ctx, old_vbuf);
-               if (!vbuf) {
-                       dev_err(sess->core->dev, "No dst buffer available\n");
-                       kfree(new_frame);
-                       return NULL;
-               }
-       }
-
        new_frame->vbuf = vbuf;
        new_frame->index = vbuf->vb2_buf.index;
        new_frame->intra_only = param->p.intra_only;
@@ -1267,8 +1278,10 @@ static void codec_vp9_process_frame(struct 
amvdec_session *sess)
                codec_vp9_rm_noshow_frame(sess);
 
        vp9->cur_frame = codec_vp9_get_new_frame(sess);
-       if (!vp9->cur_frame)
+       if (!vp9->cur_frame) {
+               amvdec_abort(sess);
                return;
+       }
 
        pr_debug("frame %d: type: %08X; show_exist: %u; show: %u, intra_only: 
%u\n",
                 vp9->cur_frame->index,
diff --git a/drivers/staging/media/meson/vdec/esparser.c 
b/drivers/staging/media/meson/vdec/esparser.c
index db7022707ff8..814bb0587e3b 100644
--- a/drivers/staging/media/meson/vdec/esparser.c
+++ b/drivers/staging/media/meson/vdec/esparser.c
@@ -301,21 +301,19 @@ esparser_queue(struct amvdec_session *sess, struct 
vb2_v4l2_buffer *vbuf)
        u32 offset;
        u32 pad_size;
 
-       /*
-        * When max ref frame is held by VP9, this should be -= 3 to prevent a
-        * shortage of CAPTURE buffers on the decoder side.
-        * For the future, a good enhancement of the way this is handled could
-        * be to notify new capture buffers to the decoding modules, so that
-        * they could pause when there is no capture buffer available and
-        * resume on this notification.
-        */
-       if (sess->fmt_out->pixfmt == V4L2_PIX_FMT_VP9) {
-               if (codec_ops->num_pending_bufs)
-                       num_dst_bufs = codec_ops->num_pending_bufs(sess);
-
+       if (codec_ops->num_pending_bufs) {
+               num_dst_bufs = codec_ops->num_pending_bufs(sess);
                num_dst_bufs += v4l2_m2m_num_dst_bufs_ready(sess->m2m_ctx);
+               /*
+                * When max ref frame is held by VP9, this should be -= 4
+                * to prevent a shortage of CAPTURE buffers on the decoder side.
+                * For the future, a good enhancement of the way this is handled
+                * could be to notify new capture buffers to the decoding
+                * modules, so that they could pause when there is no capture
+                * buffer available and resume on this notification.
+                */
                if (sess->fmt_out->pixfmt == V4L2_PIX_FMT_VP9)
-                       num_dst_bufs -= 3;
+                       num_dst_bufs -= 4;
 
                if (esparser_vififo_get_free_space(sess) < payload_size ||
                    atomic_read(&sess->esparser_queued_bufs) >= num_dst_bufs)
-- 
2.22.0

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