backend/session: fix KMS device filtering
As explained in [1], user-space should perform a drmModeGetResources
call to figure out whether a device supports KMS.
[1]:
@@ -265,12 +265,20 @@ static struct wlr_device *open_if_kms(struct wlr_session *restrict session,
return NULL;
}
- drmVersion *ver = drmGetVersion(dev->fd);
- if (!ver) {
+ // The kernel errors out with EOPNOTSUPP if DRIVER_MODESET isn't set
+ drmModeRes *res = drmModeGetResources(dev->fd);
+ if (!res) {
+ if (errno != EOPNOTSUPP) {
+ wlr_log_errno(WLR_ERROR, "drmModeGetResources(%s) failed", path);
+ }
+ goto out_dev;
+ }
+ if (res->count_crtcs == 0) {
+ drmModeFreeResources(res);
goto out_dev;
}
+ drmModeFreeResources(res);
- drmFreeVersion(ver);
return dev;
out_dev:
