The bitstream prefetch unit reads data in 256 byte blocks with some kind
of queueing. For the decoder to see data up to a desired position in the
next run, the bitstream has to be filled for 2 256 byte blocks past that
position aligned up to the next 256 byte boundary.
This should make sure we never run into a buffer underrun condition if
userspace does not supply new input buffers fast enough.
Signed-off-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
---
drivers/media/platform/coda/coda-common.c | 13 ++++++++-----
drivers/media/platform/coda/coda.h | 12 ++++++++++++
2 files changed, 20 insertions(+), 5 deletions(-)
diff --git a/drivers/media/platform/coda/coda-common.c b/drivers/media/platform/coda/coda-common.c
index c53ecc884e15..c7a274c60ff9 100644
--- a/drivers/media/platform/coda/coda-common.c
+++ b/drivers/media/platform/coda/coda-common.c
@@ -1272,6 +1272,7 @@ static int coda_job_ready(void *m2m_priv)
bool stream_end = ctx->bit_stream_param &
CODA_BIT_STREAM_END_FLAG;
int num_metas = ctx->num_metas;
+ struct coda_buffer_meta *meta;
unsigned int count;
count = hweight32(ctx->frm_dis_flg);
@@ -1292,16 +1293,18 @@ static int coda_job_ready(void *m2m_priv)
if (!stream_end && (num_metas + src_bufs) < 2) {
v4l2_dbg(1, coda_debug, &ctx->dev->v4l2_dev,
- "%d: not ready: need 2 buffers available (%d, %d)\n",
+ "%d: not ready: need 2 buffers available (queue:%d + bitstream:%d)\n",
ctx->idx, num_metas, src_bufs);
return 0;
}
- if (!src_bufs && !stream_end &&
- (coda_get_bitstream_payload(ctx) < 512)) {
+ meta = list_first_entry(&ctx->buffer_meta_list,
+ struct coda_buffer_meta, list);
+ if (!coda_bitstream_can_fetch_past(ctx, meta->end) &&
+ !stream_end) {
v4l2_dbg(1, coda_debug, &ctx->dev->v4l2_dev,
- "%d: not ready: not enough bitstream data (%d).\n",
- ctx->idx, coda_get_bitstream_payload(ctx));
+ "not ready: not enough bitstream data to read past %u (%u)\n",
+ meta->end, ctx->bitstream_fifo.kfifo.in);
return 0;
}
}
diff --git a/drivers/media/platform/coda/coda.h b/drivers/media/platform/coda/coda.h
index 00d0fa50bcd1..6cb19f47cbed 100644
--- a/drivers/media/platform/coda/coda.h
+++ b/drivers/media/platform/coda/coda.h
@@ -295,6 +295,18 @@ static inline unsigned int coda_get_bitstream_payload(struct coda_ctx *ctx)
return kfifo_len(&ctx->bitstream_fifo);
}
+/*
+ * The bitstream prefetcher needs to read at least 2 256 byte periods past
+ * the desired bitstream position for all data to reach the decoder.
+ */
+static inline bool coda_bitstream_can_fetch_past(struct coda_ctx *ctx,
+ unsigned int pos)
+{
+ return (int)(ctx->bitstream_fifo.kfifo.in - ALIGN(pos, 256)) > 512;
+}
+
+bool coda_bitstream_can_fetch_past(struct coda_ctx *ctx, unsigned int pos);
+
void coda_bit_stream_end_flag(struct coda_ctx *ctx);
void coda_m2m_buf_done(struct coda_ctx *ctx, struct vb2_v4l2_buffer *buf,
--
2.19.1
