media: vidtv: avoid copying data for PES structs

Minimize the number of data copies and initialization at
the code, passing them as pointers instead of duplicating
the data.

The only case where we're keeping the data copy is at
vidtv_pes_write_h(), as it needs a copy of the passed
arguments. On such case, we're being more explicit.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/test-drivers/vidtv/vidtv_mux.c

@@ -270,22 +270,28 @@ static u32 vidtv_mux_packetize_access_units(struct vidtv_mux *m,
 					    struct vidtv_encoder *e)
 {
 	u32 nbytes = 0;
-
-	struct pes_write_args args = {};
+	struct pes_write_args args = {
+		.dest_buf           = m->mux_buf,
+		.dest_buf_sz        = m->mux_buf_sz,
+		.pid                = be16_to_cpu(e->es_pid),
+		.encoder_id         = e->id,
+		.stream_id          = be16_to_cpu(e->stream_id),
+		.send_pts           = true,  /* forbidden value '01'... */
+		.send_dts           = false, /* ...for PTS_DTS flags    */
+	};
 	u32 initial_offset = m->mux_buf_offset;
 	struct vidtv_access_unit *au = e->access_units;
-
 	u8 *buf = NULL;
-	struct vidtv_mux_pid_ctx *pid_ctx = vidtv_mux_create_pid_ctx_once(m,
-									  be16_to_cpu(e->es_pid));
+	struct vidtv_mux_pid_ctx *pid_ctx;
 
-	args.dest_buf           = m->mux_buf;
-	args.dest_buf_sz        = m->mux_buf_sz;
-	args.pid                = be16_to_cpu(e->es_pid);
-	args.encoder_id         = e->id;
-	args.continuity_counter = &pid_ctx->cc;
-	args.stream_id          = be16_to_cpu(e->stream_id);
+	/* see SMPTE 302M clause 6.4 */
+	if (args.encoder_id == S302M) {
+		args.send_dts = false;
 		args.send_pts = true;
+	}
+
+	pid_ctx = vidtv_mux_create_pid_ctx_once(m, be16_to_cpu(e->es_pid));
+	args.continuity_counter = &pid_ctx->cc;
 
 	while (au) {
 		buf                  = e->encoder_buf + au->offset;
@@ -295,7 +301,7 @@ static u32 vidtv_mux_packetize_access_units(struct vidtv_mux *m,
 		args.pts             = au->pts;
 		args.pcr	     = m->timing.clk;
 
-		m->mux_buf_offset += vidtv_pes_write_into(args);
+		m->mux_buf_offset += vidtv_pes_write_into(&args);
 
 		au = au->next;
 	}

drivers/media/test-drivers/vidtv/vidtv_pes.h

@@ -185,6 +185,6 @@ struct pes_write_args {
  * equal to the size of the access unit, since we need space for PES headers, TS headers
  * and padding bytes, if any.
  */
-u32 vidtv_pes_write_into(struct pes_write_args args);
+u32 vidtv_pes_write_into(struct pes_write_args *args);
 
 #endif // VIDTV_PES_H