1 files changed, 251 insertions, 0 deletions
diff --git a/backend/drm/fb.c b/backend/drm/fb.c
new file mode 100644
index 00000000..24d80583
--- /dev/null
+++ b/backend/drm/fb.c
@@ -0,0 +1,251 @@
+#include <drm_fourcc.h>
+#include <stdlib.h>
+#include <wlr/render/drm_format_set.h>
+#include <wlr/types/wlr_buffer.h>
+#include <wlr/util/addon.h>
+#include <wlr/util/log.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+#include "backend/drm/drm.h"
+#include "backend/drm/fb.h"
+#include "render/pixel_format.h"
+
+void drm_fb_clear(struct wlr_drm_fb **fb_ptr) {
+	if (*fb_ptr == NULL) {
+		return;
+	}
+
+	struct wlr_drm_fb *fb = *fb_ptr;
+	wlr_buffer_unlock(fb->wlr_buf); // may destroy the buffer
+
+	*fb_ptr = NULL;
+}
+
+struct wlr_drm_fb *drm_fb_lock(struct wlr_drm_fb *fb) {
+	wlr_buffer_lock(fb->wlr_buf);
+	return fb;
+}
+
+static void drm_fb_handle_destroy(struct wlr_addon *addon) {
+	struct wlr_drm_fb *fb = wl_container_of(addon, fb, addon);
+	drm_fb_destroy(fb);
+}
+
+static const struct wlr_addon_interface fb_addon_impl = {
+	.name = "wlr_drm_fb",
+	.destroy = drm_fb_handle_destroy,
+};
+
+static uint32_t get_fb_for_bo(struct wlr_drm_backend *drm,
+		struct wlr_dmabuf_attributes *dmabuf, uint32_t handles[static 4]) {
+	uint64_t modifiers[4] = {0};
+	for (int i = 0; i < dmabuf->n_planes; i++) {
+		// KMS requires all BO planes to have the same modifier
+		modifiers[i] = dmabuf->modifier;
+	}
+
+	uint32_t id = 0;
+	if (drm->addfb2_modifiers && dmabuf->modifier != DRM_FORMAT_MOD_INVALID) {
+		if (drmModeAddFB2WithModifiers(drm->fd, dmabuf->width, dmabuf->height,
+				dmabuf->format, handles, dmabuf->stride, dmabuf->offset,
+				modifiers, &id, DRM_MODE_FB_MODIFIERS) != 0) {
+			wlr_log_errno(WLR_DEBUG, "drmModeAddFB2WithModifiers failed");
+		}
+	} else {
+		if (dmabuf->modifier != DRM_FORMAT_MOD_INVALID &&
+				dmabuf->modifier != DRM_FORMAT_MOD_LINEAR) {
+			wlr_log(WLR_ERROR, "Cannot import DRM framebuffer with explicit "
+				"modifier 0x%"PRIX64, dmabuf->modifier);
+			return 0;
+		}
+
+		int ret = drmModeAddFB2(drm->fd, dmabuf->width, dmabuf->height,
+			dmabuf->format, handles, dmabuf->stride, dmabuf->offset, &id, 0);
+		if (ret != 0 && dmabuf->format == DRM_FORMAT_ARGB8888 &&
+				dmabuf->n_planes == 1 && dmabuf->offset[0] == 0) {
+			// Some big-endian machines don't support drmModeAddFB2. Try a
+			// last-resort fallback for ARGB8888 buffers, like Xorg's
+			// modesetting driver does.
+			wlr_log(WLR_DEBUG, "drmModeAddFB2 failed (%s), falling back to "
+				"legacy drmModeAddFB", strerror(-ret));
+
+			uint32_t depth = 32;
+			uint32_t bpp = 32;
+			ret = drmModeAddFB(drm->fd, dmabuf->width, dmabuf->height, depth,
+				bpp, dmabuf->stride[0], handles[0], &id);
+			if (ret != 0) {
+				wlr_log_errno(WLR_DEBUG, "drmModeAddFB failed");
+			}
+		} else if (ret != 0) {
+			wlr_log_errno(WLR_DEBUG, "drmModeAddFB2 failed");
+		}
+	}
+
+	return id;
+}
+
+static void close_all_bo_handles(struct wlr_drm_backend *drm,
+		uint32_t handles[static 4]) {
+	for (int i = 0; i < 4; ++i) {
+		if (handles[i] == 0) {
+			continue;
+		}
+
+		// If multiple planes share the same BO handle, avoid double-closing it
+		bool already_closed = false;
+		for (int j = 0; j < i; ++j) {
+			if (handles[i] == handles[j]) {
+				already_closed = true;
+				break;
+			}
+		}
+		if (already_closed) {
+			continue;
+		}
+
+		if (drmCloseBufferHandle(drm->fd, handles[i]) != 0) {
+			wlr_log_errno(WLR_ERROR, "drmCloseBufferHandle failed");
+		}
+	}
+}
+
+static void drm_poisoned_fb_handle_destroy(struct wlr_addon *addon) {
+	wlr_addon_finish(addon);
+	free(addon);
+}
+
+static const struct wlr_addon_interface poisoned_fb_addon_impl = {
+	.name = "wlr_drm_poisoned_fb",
+	.destroy = drm_poisoned_fb_handle_destroy,
+};
+
+static bool is_buffer_poisoned(struct wlr_drm_backend *drm,
+		struct wlr_buffer *buf) {
+	return wlr_addon_find(&buf->addons, drm, &poisoned_fb_addon_impl) != NULL;
+}
+
+/**
+ * Mark the buffer as "poisoned", ie. it cannot be imported into KMS. This
+ * allows us to avoid repeatedly trying to import it when it's not
+ * scanout-capable.
+ */
+static void poison_buffer(struct wlr_drm_backend *drm,
+		struct wlr_buffer *buf) {
+	struct wlr_addon *addon = calloc(1, sizeof(*addon));
+	if (addon == NULL) {
+		wlr_log_errno(WLR_ERROR, "Allocation failed");
+		return;
+	}
+	wlr_addon_init(addon, &buf->addons, drm, &poisoned_fb_addon_impl);
+	wlr_log(WLR_DEBUG, "Poisoning buffer");
+}
+
+static struct wlr_drm_fb *drm_fb_create(struct wlr_drm_backend *drm,
+		struct wlr_buffer *buf, const struct wlr_drm_format_set *formats) {
+	struct wlr_dmabuf_attributes attribs;
+	if (!wlr_buffer_get_dmabuf(buf, &attribs)) {
+		wlr_log(WLR_DEBUG, "Failed to get DMA-BUF from buffer");
+		return NULL;
+	}
+
+	if (is_buffer_poisoned(drm, buf)) {
+		wlr_log(WLR_DEBUG, "Buffer is poisoned");
+		return NULL;
+	}
+
+	struct wlr_drm_fb *fb = calloc(1, sizeof(*fb));
+	if (!fb) {
+		wlr_log_errno(WLR_ERROR, "Allocation failed");
+		return NULL;
+	}
+
+	if (formats && !wlr_drm_format_set_has(formats, attribs.format,
+			attribs.modifier)) {
+		// The format isn't supported by the plane. Try stripping the alpha
+		// channel, if any.
+		const struct wlr_pixel_format_info *info =
+			drm_get_pixel_format_info(attribs.format);
+		if (info != NULL && info->opaque_substitute != DRM_FORMAT_INVALID &&
+				wlr_drm_format_set_has(formats, info->opaque_substitute, attribs.modifier)) {
+			attribs.format = info->opaque_substitute;
+		} else {
+			wlr_log(WLR_DEBUG, "Buffer format 0x%"PRIX32" with modifier "
+				"0x%"PRIX64" cannot be scanned out",
+				attribs.format, attribs.modifier);
+			goto error_fb;
+		}
+	}
+
+	uint32_t handles[4] = {0};
+	for (int i = 0; i < attribs.n_planes; ++i) {
+		int ret = drmPrimeFDToHandle(drm->fd, attribs.fd[i], &handles[i]);
+		if (ret != 0) {
+			wlr_log_errno(WLR_DEBUG, "drmPrimeFDToHandle failed");
+			goto error_bo_handle;
+		}
+	}
+
+	fb->id = get_fb_for_bo(drm, &attribs, handles);
+	if (!fb->id) {
+		wlr_log(WLR_DEBUG, "Failed to import BO in KMS");
+		poison_buffer(drm, buf);
+		goto error_bo_handle;
+	}
+
+	close_all_bo_handles(drm, handles);
+
+	fb->backend = drm;
+	fb->wlr_buf = buf;
+
+	wlr_addon_init(&fb->addon, &buf->addons, drm, &fb_addon_impl);
+	wl_list_insert(&drm->fbs, &fb->link);
+
+	return fb;
+
+error_bo_handle:
+	close_all_bo_handles(drm, handles);
+error_fb:
+	free(fb);
+	return NULL;
+}
+
+void drm_fb_destroy(struct wlr_drm_fb *fb) {
+	struct wlr_drm_backend *drm = fb->backend;
+
+	wl_list_remove(&fb->link);
+	wlr_addon_finish(&fb->addon);
+
+	int ret = drmModeCloseFB(drm->fd, fb->id);
+	if (ret == -EINVAL) {
+		ret = drmModeRmFB(drm->fd, fb->id);
+	}
+	if (ret != 0) {
+		wlr_log(WLR_ERROR, "Failed to close FB: %s", strerror(-ret));
+	}
+
+	free(fb);
+}
+
+bool drm_fb_import(struct wlr_drm_fb **fb_ptr, struct wlr_drm_backend *drm,
+		struct wlr_buffer *buf, const struct wlr_drm_format_set *formats) {
+	struct wlr_drm_fb *fb;
+	struct wlr_addon *addon = wlr_addon_find(&buf->addons, drm, &fb_addon_impl);
+	if (addon != NULL) {
+		fb = wl_container_of(addon, fb, addon);
+	} else {
+		fb = drm_fb_create(drm, buf, formats);
+		if (!fb) {
+			return false;
+		}
+	}
+
+	wlr_buffer_lock(buf);
+	drm_fb_move(fb_ptr, &fb);
+	return true;
+}
+
+void drm_fb_move(struct wlr_drm_fb **new, struct wlr_drm_fb **old) {
+	drm_fb_clear(new);
+	*new = *old;
+	*old = NULL;
+}