screencast: allocate dmabuf with implicit modifier

This is using the older gbm api without support for explicit modifiers.
This is required to support AMD gpus using the GFX8 or older
architecture and older intel gpus.

include/screencast_common.h

@@ -85,6 +85,8 @@ struct xdpw_buffer {
 	uint32_t stride;
 	uint32_t offset;
 
+	struct gbm_bo *bo;
+
 	struct wl_buffer *buffer;
 };
 

src/screencast/pipewire_screencast.c

@@ -186,6 +186,9 @@ static void pwr_handle_stream_add_buffer(void *data, struct pw_buffer *buffer) {
 	if ((d[0].type & (1u << SPA_DATA_MemFd)) > 0) {
 		assert(cast->buffer_type == WL_SHM);
 		d[0].type = SPA_DATA_MemFd;
+	} else if ((d[0].type & (1u << SPA_DATA_DmaBuf)) > 0) {
+		assert(cast->buffer_type == DMABUF);
+		d[0].type = SPA_DATA_DmaBuf;
 	} else {
 		logprint(ERROR, "pipewire: unsupported buffer type");
 		cast->err = 1;

src/screencast/screencast_common.c

@@ -7,6 +7,7 @@
 #include <unistd.h>
 #include <libdrm/drm_fourcc.h>
 #include <xf86drm.h>
+#include "linux-dmabuf-unstable-v1-client-protocol.h"
 
 #include "logger.h"
 
@@ -135,7 +136,52 @@ struct xdpw_buffer *xdpw_buffer_create(struct xdpw_screencast_instance *cast,
 		}
 		break;
 	case DMABUF:
-		abort();
+		buffer->bo = gbm_bo_create(cast->ctx->gbm,
+				frame_info->width, frame_info->height, frame_info->format,
+				GBM_BO_USE_RENDERING);
+		if (buffer->bo == NULL) {
+			logprint(ERROR, "xdpw: failed to create gbm_bo");
+			free(buffer);
+			return NULL;
+		}
+
+		struct zwp_linux_buffer_params_v1 *params;
+		params = zwp_linux_dmabuf_v1_create_params(cast->ctx->linux_dmabuf);
+		if (!params) {
+			logprint(ERROR, "xdpw: failed to create linux_buffer_params");
+			gbm_bo_destroy(buffer->bo);
+			free(buffer);
+			return NULL;
+		}
+
+		buffer->size = 0;
+		buffer->stride = gbm_bo_get_stride(buffer->bo);
+		buffer->offset = gbm_bo_get_offset(buffer->bo, 0);
+		uint64_t mod = gbm_bo_get_modifier(buffer->bo);
+		buffer->fd = gbm_bo_get_fd(buffer->bo);
+
+		if (buffer->fd < 0) {
+			logprint(ERROR, "xdpw: failed to get file descriptor");
+			zwp_linux_buffer_params_v1_destroy(params);
+			gbm_bo_destroy(buffer->bo);
+			free(buffer);
+			return NULL;
+		}
+
+		zwp_linux_buffer_params_v1_add(params, buffer->fd, 0, buffer->offset, buffer->stride,
+			mod >> 32, mod & 0xffffffff);
+		buffer->buffer = zwp_linux_buffer_params_v1_create_immed(params,
+			buffer->width, buffer->height,
+			buffer->format, /* flags */ 0);
+		zwp_linux_buffer_params_v1_destroy(params);
+
+		if (!buffer->buffer) {
+			logprint(ERROR, "xdpw: failed to create buffer");
+			gbm_bo_destroy(buffer->bo);
+			close(buffer->fd);
+			free(buffer);
+			return NULL;
+		}
 	}
 
 	return buffer;
@@ -143,6 +189,9 @@ struct xdpw_buffer *xdpw_buffer_create(struct xdpw_screencast_instance *cast,
 
 void xdpw_buffer_destroy(struct xdpw_buffer *buffer) {
 	wl_buffer_destroy(buffer->buffer);
+	if (buffer->buffer_type == DMABUF) {
+		gbm_bo_destroy(buffer->bo);
+	}
 	close(buffer->fd);
 	wl_list_remove(&buffer->link);
 	free(buffer);