render: add DRM dumb buffer allocator

include/render/drm_dumb_allocator.h

@@ -0,0 +1,37 @@
+#ifndef RENDER_DRM_DUMB_ALLOCATOR_H
+#define RENDER_DRM_DUMB_ALLOCATOR_H
+
+#include "render/allocator.h"
+
+#include <wlr/types/wlr_buffer.h>
+
+struct wlr_drm_dumb_buffer {
+	struct wlr_buffer base;
+	struct wl_list link; // wlr_drm_dumb_allocator::buffers
+
+	int drm_fd; // -1 if the allocator has been destroyed
+	struct wlr_dmabuf_attributes dmabuf;
+
+	uint32_t format;
+	uint32_t handle;
+	uint32_t stride;
+	uint32_t width, height;
+
+	uint64_t size;
+	void *data;
+};
+
+struct wlr_drm_dumb_allocator {
+	struct wlr_allocator base;
+	struct wl_list buffers; // wlr_drm_dumb_buffer::link
+	int drm_fd;
+};
+
+/**
+ * Creates a new drm dumb allocator from a DRM FD.
+ *
+ * Does not take ownership over the FD.
+ */
+struct wlr_allocator *wlr_drm_dumb_allocator_create(int fd);
+
+#endif

render/allocator.c

@@ -1,4 +1,3 @@
-#define _POSIX_C_SOURCE 200809L
 #include <assert.h>
 #include <stdlib.h>
 #include <wlr/util/log.h>
@@ -7,6 +6,7 @@
 #include "render/allocator.h"
 #include "render/gbm_allocator.h"
 #include "render/shm_allocator.h"
+#include "render/drm_dumb_allocator.h"
 #include "render/wlr_renderer.h"
 #include "types/wlr_buffer.h"
 
@@ -43,6 +43,16 @@ struct wlr_allocator *allocator_autocreate_with_drm_fd(
 		wlr_log(WLR_DEBUG, "Failed to create shm allocator");
 	}
 
+	uint32_t drm_caps = WLR_BUFFER_CAP_DMABUF | WLR_BUFFER_CAP_DATA_PTR;
+	if ((backend_caps & drm_caps) && (renderer_caps & drm_caps)
+			&& drm_fd != -1) {
+		wlr_log(WLR_DEBUG, "Trying to create drm dumb allocator");
+		if ((alloc = wlr_drm_dumb_allocator_create(drm_fd)) != NULL) {
+			return alloc;
+		}
+		wlr_log(WLR_DEBUG, "Failed to create drm dumb allocator");
+	}
+
 	wlr_log(WLR_ERROR, "Failed to create allocator");
 	return NULL;
 }

render/drm_dumb_allocator.c

@@ -0,0 +1,237 @@
+#define _POSIX_C_SOURCE 200809L
+
+#include <assert.h>
+#include <drm_fourcc.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <wlr/util/log.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include <wlr/backend.h>
+#include <wlr/backend/session.h>
+
+#include "render/drm_dumb_allocator.h"
+#include "render/pixel_format.h"
+
+static const struct wlr_buffer_impl buffer_impl;
+
+static struct wlr_drm_dumb_buffer *drm_dumb_buffer_from_buffer(
+		struct wlr_buffer *wlr_buf) {
+	assert(wlr_buf->impl == &buffer_impl);
+	return (struct wlr_drm_dumb_buffer *)wlr_buf;
+}
+
+static void finish_buffer(struct wlr_drm_dumb_buffer *buf) {
+	if (buf->data) {
+		munmap(buf->data, buf->size);
+	}
+
+	wlr_dmabuf_attributes_finish(&buf->dmabuf);
+
+	if (buf->drm_fd >= 0) {
+		struct drm_mode_destroy_dumb destroy = { .handle = buf->handle };
+		if (drmIoctl(buf->drm_fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy)) {
+			wlr_log_errno(WLR_ERROR, "Failed to destroy DRM dumb buffer");
+		}
+	}
+
+	wl_list_remove(&buf->link);
+}
+
+static struct wlr_drm_dumb_buffer *create_buffer(
+		struct wlr_drm_dumb_allocator *alloc, int width, int height,
+		const struct wlr_drm_format *format) {
+	struct wlr_drm_dumb_buffer *buffer = calloc(1, sizeof(*buffer));
+	if (buffer == NULL) {
+		return NULL;
+	}
+	wlr_buffer_init(&buffer->base, &buffer_impl, width, height);
+	wl_list_insert(&alloc->buffers, &buffer->link);
+
+	const struct wlr_pixel_format_info *info =
+		drm_get_pixel_format_info(format->format);
+	if (info == NULL) {
+		wlr_log(WLR_ERROR, "DRM format 0x%"PRIX32" not supported",
+			format->format);
+		goto create_err;
+	}
+
+	struct drm_mode_create_dumb create = {0};
+	create.width = (uint32_t)width;
+	create.height = (uint32_t)height;
+	create.bpp = info->bpp;
+
+	if (drmIoctl(alloc->drm_fd, DRM_IOCTL_MODE_CREATE_DUMB, &create) != 0) {
+		wlr_log_errno(WLR_ERROR, "Failed to create DRM dumb buffer");
+		goto create_err;
+	}
+
+	buffer->width = create.width;
+	buffer->height = create.height;
+
+	buffer->stride = create.pitch;
+	buffer->handle = create.handle;
+	buffer->format = format->format;
+
+	buffer->drm_fd = alloc->drm_fd;
+
+	struct drm_mode_map_dumb map = {0};
+	map.handle = buffer->handle;
+
+	if (drmIoctl(alloc->drm_fd, DRM_IOCTL_MODE_MAP_DUMB, &map) != 0) {
+		wlr_log_errno(WLR_ERROR, "Failed to map DRM dumb buffer");
+		goto create_destroy;
+	}
+
+	buffer->data = mmap(NULL, create.size, PROT_READ | PROT_WRITE, MAP_SHARED,
+			alloc->drm_fd, map.offset);
+	if (buffer->data == MAP_FAILED) {
+		wlr_log_errno(WLR_ERROR, "Failed to mmap DRM dumb buffer");
+		goto create_destroy;
+	}
+
+	buffer->size = create.size;
+
+	memset(buffer->data, 0, create.size);
+
+	int prime_fd;
+	if (drmPrimeHandleToFD(alloc->drm_fd, buffer->handle, DRM_CLOEXEC,
+			&prime_fd) != 0) {
+		wlr_log_errno(WLR_ERROR, "Failed to get PRIME handle from GEM handle");
+		goto create_destroy;
+	}
+
+	buffer->dmabuf = (struct wlr_dmabuf_attributes){
+		.width = buffer->width,
+		.height = buffer->height,
+		.format = format->format,
+		.modifier = DRM_FORMAT_MOD_INVALID,
+		.n_planes = 1,
+		.offset[0] = 0,
+		.stride[0] = buffer->stride,
+		.fd[0] = prime_fd,
+	};
+
+	wlr_log(WLR_DEBUG, "Allocated %"PRIu32"x%"PRIu32" DRM dumb buffer",
+			buffer->width, buffer->height);
+
+	return buffer;
+
+create_destroy:
+	finish_buffer(buffer);
+create_err:
+	free(buffer);
+	return NULL;
+}
+
+static bool buffer_get_data_ptr(struct wlr_buffer *wlr_buffer, void **data,
+		uint32_t *format, size_t *stride) {
+	struct wlr_drm_dumb_buffer *buf = drm_dumb_buffer_from_buffer(wlr_buffer);
+	*data = buf->data;
+	*stride = buf->stride;
+	*format = buf->format;
+	return true;
+}
+
+static bool buffer_get_dmabuf(struct wlr_buffer *wlr_buffer,
+		struct wlr_dmabuf_attributes *attribs) {
+	struct wlr_drm_dumb_buffer *buf = drm_dumb_buffer_from_buffer(wlr_buffer);
+	memcpy(attribs, &buf->dmabuf, sizeof(buf->dmabuf));
+	return true;
+}
+
+static void buffer_destroy(struct wlr_buffer *wlr_buffer) {
+	struct wlr_drm_dumb_buffer *buf = drm_dumb_buffer_from_buffer(wlr_buffer);
+	finish_buffer(buf);
+	free(buf);
+}
+
+static const struct wlr_buffer_impl buffer_impl = {
+	.destroy = buffer_destroy,
+	.get_dmabuf = buffer_get_dmabuf,
+	.get_data_ptr = buffer_get_data_ptr,
+};
+
+static const struct wlr_allocator_interface allocator_impl;
+
+static struct wlr_drm_dumb_allocator *drm_dumb_alloc_from_alloc(
+		struct wlr_allocator *wlr_alloc) {
+	assert(wlr_alloc->impl == &allocator_impl);
+	return (struct wlr_drm_dumb_allocator *)wlr_alloc;
+}
+
+static struct wlr_buffer *allocator_create_buffer(
+		struct wlr_allocator *wlr_alloc, int width, int height,
+		const struct wlr_drm_format *drm_format) {
+	struct wlr_drm_dumb_allocator *alloc = drm_dumb_alloc_from_alloc(wlr_alloc);
+	struct wlr_drm_dumb_buffer *buffer = create_buffer(alloc, width, height,
+			drm_format);
+	if (buffer == NULL) {
+		return NULL;
+	}
+	return &buffer->base;
+}
+
+static void allocator_destroy(struct wlr_allocator *wlr_alloc) {
+	struct wlr_drm_dumb_allocator *alloc = drm_dumb_alloc_from_alloc(wlr_alloc);
+
+	struct wlr_drm_dumb_buffer *buf, *buf_tmp;
+	wl_list_for_each_safe(buf, buf_tmp, &alloc->buffers, link) {
+		buf->drm_fd = -1;
+		wl_list_remove(&buf->link);
+		wl_list_init(&buf->link);
+	}
+
+	close(alloc->drm_fd);
+	free(alloc);
+}
+
+static const struct wlr_allocator_interface allocator_impl = {
+	.create_buffer = allocator_create_buffer,
+	.destroy = allocator_destroy,
+};
+
+struct wlr_allocator *wlr_drm_dumb_allocator_create(int fd) {
+	/* Re-open the DRM node to avoid GEM handle ref'counting issues. See:
+	 * https://gitlab.freedesktop.org/mesa/drm/-/merge_requests/110
+	 * TODO: don't assume we have the permission to just open the DRM node,
+	 * find another way to re-open it.
+	 */
+	char *path = drmGetDeviceNameFromFd2(fd);
+	int drm_fd = open(path, O_RDWR | O_CLOEXEC);
+	if (drm_fd < 0) {
+		wlr_log_errno(WLR_ERROR, "Failed to open DRM node %s", path);
+		free(path);
+		return NULL;
+	}
+
+	uint64_t has_dumb = 0;
+	if (drmGetCap(drm_fd, DRM_CAP_DUMB_BUFFER, &has_dumb) < 0) {
+		wlr_log(WLR_ERROR, "Failed to get DRM capabilities");
+		free(path);
+		return NULL;
+	}
+
+	if (has_dumb == 0) {
+		wlr_log(WLR_ERROR, "DRM dumb buffers not supported");
+		free(path);
+		return NULL;
+	}
+
+	struct wlr_drm_dumb_allocator *alloc = calloc(1, sizeof(*alloc));
+	if (alloc == NULL) {
+		free(path);
+		return NULL;
+	}
+	wlr_allocator_init(&alloc->base, &allocator_impl);
+
+	alloc->drm_fd = drm_fd;
+	wl_list_init(&alloc->buffers);
+
+	wlr_log(WLR_DEBUG, "Created DRM dumb allocator with node %s", path);
+	free(path);
+	return &alloc->base;
+}

render/meson.build

@@ -15,6 +15,7 @@ wlr_files += files(
 	'swapchain.c',
 	'wlr_renderer.c',
 	'wlr_texture.c',
+	'drm_dumb_allocator.c',
 )
 
 egl = dependency('egl', required: 'gles2' in renderers)