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Posted to commits@nuttx.apache.org by "linguini1 (via GitHub)" <gi...@apache.org> on 2025/11/07 21:14:12 UTC
[I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
linguini1 opened a new issue, #17292:
URL: https://github.com/apache/nuttx/issues/17292
### Is your feature request related to a problem? Please describe.
The RPi4B videocore supports accessing a framebuffer interface for outputting graphics on the mini-HDMI ports. There is no support for this on NuttX yet.
### Describe the solution you'd like
A basic framebuffer driver for the Pi4B should be implemented so that some basic graphics and some of the demos can be run.
### Describe alternatives you've considered
_No response_
### Verification
- [x] I have verified before submitting the report.
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Re: [I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
Posted by "acassis (via GitHub)" <gi...@apache.org>.
acassis closed issue #17292: [FEATURE] RPi4B basic framebuffer driver
URL: https://github.com/apache/nuttx/issues/17292
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Re: [I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
Posted by "linguini1 (via GitHub)" <gi...@apache.org>.
linguini1 commented on issue #17292:
URL: https://github.com/apache/nuttx/issues/17292#issuecomment-3505961106
The frame-buffer virtual resolution always appears as 2x2, with the frame buffer size being 1024 bytes and GRB colour ordering when I attempt to set up the frame buffer by making multiple, individual requests to the mailbox. Ex:
- Get physical display size (fine)
- Set virtual display size to physical size (returns virtual size of 2x2 px)
- Check colour ordering (gets GRB)
- Set ordering to RGB (refused)
- Get frame buffer (1024 bytes in size)
I can then draw to the frame buffer, which results in a blurry, half-purple screen. Subsequent calls to the mailbox time out, and sometimes the system eventually crashes.
On the other hand, if I take the approach I saw others use (bundle all these commands into one large mailbox request), the frame buffer works just fine. This does require that a screen resolution be specified in advance, the Pi 4B will request that from the display. No fancy negotiation or anything, that is done in the VideoCore which is a black box.
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Re: [I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
Posted by "TimJTi (via GitHub)" <gi...@apache.org>.
TimJTi commented on issue #17292:
URL: https://github.com/apache/nuttx/issues/17292#issuecomment-3506124687
Framebuffer demo app works on my board; I'm away until Tuesday but I can grab a video or whatever of what it does when I'm back if it helps?
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Re: [I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
Posted by "linguini1 (via GitHub)" <gi...@apache.org>.
linguini1 commented on issue #17292:
URL: https://github.com/apache/nuttx/issues/17292#issuecomment-3505964878
Also the frame buffer example app does not have any documentation that I could find. It needs some, especially an image of what the output should look like.
I also think there should be some documentation about how to properly implement the frame-buffer driver lower-half. It would have saved me time.
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Re: [I] [FEATURE] RPi4B basic framebuffer driver [nuttx]
Posted by "linguini1 (via GitHub)" <gi...@apache.org>.
linguini1 commented on issue #17292:
URL: https://github.com/apache/nuttx/issues/17292#issuecomment-3506595875
> Framebuffer demo app works on my board; I'm away until Tuesday but I can grab a video or whatever of what it does when I'm back if it helps?
Is it the `fb` application or the LVGL demo?
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