pip3 install --user rockx提示磁盘没有空间

安装rockx提示没有磁盘空间，但是使用df -h查看 / 目录空间还有很多。请问知道什么原因么？
详情请看图片。

[toybrick@rk1808 tmp]$ pip3 install --user rockx
Collecting rockx
  Downloading http://repo.rock-chips.com/pypi/ ... .0-py3-none-any.whl (284.7MB)
    100% |████████████████████████████████| 284.7MB 1.3MB/s
Exception:
Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/pip/basecommand.py", line 215, in main
    status = self.run(options, args)
  File "/usr/lib/python3.6/site-packages/pip/commands/install.py", line 346, in run
    requirement_set.prepare_files(finder)
  File "/usr/lib/python3.6/site-packages/pip/req/req_set.py", line 380, in prepare_files
    ignore_dependencies=self.ignore_dependencies))
  File "/usr/lib/python3.6/site-packages/pip/req/req_set.py", line 620, in _prepare_file
    session=self.session, hashes=hashes)
  File "/usr/lib/python3.6/site-packages/pip/download.py", line 821, in unpack_url
    hashes=hashes
  File "/usr/lib/python3.6/site-packages/pip/download.py", line 663, in unpack_http_url
    unpack_file(from_path, location, content_type, link)
  File "/usr/lib/python3.6/site-packages/pip/utils/__init__.py", line 599, in unpack_file
    flatten=not filename.endswith('.whl')
  File "/usr/lib/python3.6/site-packages/pip/utils/__init__.py", line 501, in unzip_file
    fp.write(data)
OSError: [Errno 28] No space left on device
[toybrick@rk1808 tmp]$ df -h
Filesystem      Size  Used Avail Use% Mounted on
devtmpfs        423M     0  423M   0% /dev
tmpfs           495M     0  495M   0% /dev/shm
tmpfs           495M  268K  494M   1% /run
tmpfs           495M     0  495M   0% /sys/fs/cgroup
/dev/mmcblk0p4  7.1G  2.6G  4.2G  39% /
tmpfs           495M  278M  217M  57% /tmp
/dev/mmcblk0p3   63M   30M   31M  49% /boot
tmpfs            99M     0   99M   0% /run/user/1000

解决了，之前没有看官方文档，按照这个步骤就可以了
3.  mkdir /home/toybrick/tmp
4. export TMPDIR=/home/toybrick/tmp
5. sudo dnf install -y python3-opencv
6. pip3 install --user rockx