[BUG] DRM preview can't find DRM cards

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#922 5 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
linux, python
Domain
computer-graphics, operating-systems

Research direction

Start with examples/preview_drm.py and follow Picamera2.start_preview in picamera2.py into previews/drm_preview.py, especially the pykms.Card() call in DrmPreview._manager.add. Reproduce on the reported Raspberry Pi setup and determine why no DRM card is found; done means the DRM preview starts without the reported error.

Written by the indexing model from the issue text.

Description


# For use from the login console, when not running X Windows.

import time

from picamera2 import Picamera2, Preview

picam2 = Picamera2()
picam2.start_preview(Preview.DRM, x=100, y=100, width=480, height=320)

preview_config = picam2.create_preview_configuration({"size": (480, 320)})
picam2.configure(preview_config)

picam2.start()
time.sleep(5)

running the above script (preview_DRM.py from examples) or any snippet that tries to open up a DRM preview I get the following error message:

  File "/home/tsid/picamera2/examples/preview_drm.py", line 10, in <module>
    picam2.start_preview(Preview.DRM, x=100, y=100, width=480, height=320)
  File "/usr/lib/python3/dist-packages/picamera2/picamera2.py", line 569, in start_preview
    preview = preview_table[preview](**kwargs)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/picamera2/previews/drm_preview.py", line 56, in __init__
    self.init_drm(x, y, width, height, transform)
  File "/usr/lib/python3/dist-packages/picamera2/previews/drm_preview.py", line 78, in init_drm
    DrmPreview._manager.add(self)
  File "/usr/lib/python3/dist-packages/picamera2/previews/drm_preview.py", line 19, in add
    self.card = pykms.Card()
                ^^^^^^^^^^^^
RuntimeError: failed to find DRM cards

I'm running a raspberry pi 4B 8gb on 64bit lite OS via SSH from windows
camera used: HQ Camera module
also hooked up on the pi is a Waveshare RPi LCD C 3.5 SPI screen

Dominant language
Python
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