From 5481a235eda0477a83ef95fac7b9cc2bcea675ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20=C3=85dahl?= <jadahl@gmail.com>
Date: Tue, 11 Nov 2025 21:06:17 +0100
Subject: [PATCH] examples: Make fixate examples optionally stream DMA buffers

The video-play-fixate example will downgrade the stream to MemFd one
modifier at a time. Sometimes it's useful to test with not downgrading;
to avoid having to depend on actual DRM devices (real or virtual), fake
them by using memfd and mapping them in the sink.
---
 src/examples/video-play-fixate.c | 21 ++++++++++++++++++++-
 src/examples/video-src-fixate.c  | 25 +++++++++----------------
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/src/examples/video-play-fixate.c b/src/examples/video-play-fixate.c
index ed250d914..3c6875a15 100644
--- a/src/examples/video-play-fixate.c
+++ b/src/examples/video-play-fixate.c
@@ -13,6 +13,7 @@
 #include <unistd.h>
 #include <signal.h>
 #include <libdrm/drm_fourcc.h>
+#include <sys/mman.h>
 
 #include <spa/utils/result.h>
 #include <spa/param/video/format-utils.h>
@@ -22,6 +23,9 @@
 
 #include <pipewire/pipewire.h>
 
+/* If defined, emulate failing to import DMA buffer. */
+#define EMULATE_DMA_BUF_IMPORT_FAIL 1
+
 #define WIDTH   640
 #define HEIGHT  480
 #define RATE	30
@@ -197,10 +201,12 @@ on_process(void *_data)
 	struct pw_stream *stream = data->stream;
 	struct pw_buffer *b;
 	struct spa_buffer *buf;
+	struct spa_data *d;
 	void *sdata, *ddata;
 	int sstride, dstride, ostride;
 	uint32_t i;
 	uint8_t *src, *dst;
+	bool needs_unmap = false;
 
 	b = NULL;
 	/* dequeue and queue old buffers, use the last available
@@ -219,11 +225,13 @@ on_process(void *_data)
 	}
 
 	buf = b->buffer;
+	d = buf->datas;
 
 	pw_log_info("new buffer %p", buf);
 
 	handle_events(data);
 
+#ifdef EMULATE_DMA_BUF_IMPORT_FAIL
 	if (buf->datas[0].type == SPA_DATA_DmaBuf) {
 		// Simulate a failed import of a DmaBuf
 		// We should try another modifier
@@ -232,8 +240,17 @@ on_process(void *_data)
 		pw_loop_signal_event(pw_main_loop_get_loop(data->loop), data->reneg);
 		goto done;
 	}
+#endif
 
-	if ((sdata = buf->datas[0].data) == NULL)
+	if (buf->datas[0].type == SPA_DATA_DmaBuf) {
+		sdata = mmap(NULL, d[0].maxsize, PROT_READ,
+			MAP_SHARED, d[0].fd, d[0].mapoffset);
+		needs_unmap = true;
+	} else {
+		sdata = buf->datas[0].data;
+	}
+
+	if (sdata == NULL)
 		goto done;
 
 	if (SDL_LockTexture(data->texture, NULL, &ddata, &dstride) < 0) {
@@ -263,6 +280,8 @@ on_process(void *_data)
 	SDL_RenderPresent(data->renderer);
 
       done:
+	if (needs_unmap)
+		munmap(d[0].data, d[0].maxsize);
 	pw_stream_queue_buffer(stream, b);
 }
 
diff --git a/src/examples/video-src-fixate.c b/src/examples/video-src-fixate.c
index 53c5776c6..64eb32895 100644
--- a/src/examples/video-src-fixate.c
+++ b/src/examples/video-src-fixate.c
@@ -304,26 +304,19 @@ static void on_stream_add_buffer(void *_data, struct pw_buffer *buffer)
 #else
 		d[0].fd = -1;
 #endif
-		d[0].data = NULL;
-		return;
-	}
-
-	if ((d[0].type & (1<<SPA_DATA_MemFd)) == 0) {
-		pw_log_error("unsupported data type %08x", d[0].type);
-		return;
-	}
-
-	printf("use memfd\n");
-	/* create the memfd on the buffer, set the type and flags */
-	d[0].type = SPA_DATA_MemFd;
-	d[0].flags = SPA_DATA_FLAG_READWRITE | SPA_DATA_FLAG_MAPPABLE;
+	} else {
+		printf("use memfd\n");
+		/* create the memfd on the buffer, set the type and flags */
+		d[0].type = SPA_DATA_MemFd;
+		d[0].flags = SPA_DATA_FLAG_READWRITE | SPA_DATA_FLAG_MAPPABLE;
 #ifdef HAVE_MEMFD_CREATE
-	d[0].fd = memfd_create("video-src-fixate-memfd", MFD_CLOEXEC | MFD_ALLOW_SEALING);
+		d[0].fd = memfd_create("video-src-fixate-memfd", MFD_CLOEXEC | MFD_ALLOW_SEALING);
 #else
-	d[0].fd = -1;
+		d[0].fd = -1;
 #endif
+	}
 	if (d[0].fd == -1) {
-		pw_log_error("can't create memfd: %m");
+		pw_log_error("can't open file descriptor: %m");
 		return;
 	}
 	d[0].mapoffset = 0;