Conversation
pavel

Pavel Machek

debayer-gpu (git@gitlab.com:tui/debayer-gpu.git) tries to do debayering on GPU. But it seems OpenGL 2.1 is ... really not meant to do the computation. glReadPixels() can be used to get data off the GPU, but that does not have great performance. On PinePhone, you can only get RGBA out, but we really need RGB. Doing RGBA->RGB on CPU is easy, but it degrades performance further. I believe problem is that ISP produces a lot of data.

On Thinkpad X220, converting 400 images is like 12 seconds. If I do no processing in the fragment shader, it is still 10 seconds. X220 is able to process ~20Mpix/second on GPU. I don't believe Librem 5 will be significantly better.

If you believe GPU can be useful for task like debayering (mostly rearranging data with some additions and 2 matrix multiplies per pixel), let me know. 30Mpix/second on Librem 5 would be useful performance. #linuxphone
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martijnbraam@fosstodon.org

Martijn Braam

Reply to @pavel

@pavel it would be really great if these devices supported a slightly newer opengl version. I think it's still possible to use PBOs to get the data out more efficiently

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pavel

Pavel Machek

Reply to @martijnbraam@fosstodon.org
@martijnbraam Yeah, robot was suggesting PBOs. It would be great if someone with GPU experience could chime in, ideally saying "no, Librem 5 GPU can't handle 30MB/sec data flow" or better "yes, Librem 5 GPU can handle that easily, here is how" :-). Or maybe "No, can't work on Librem 5, but OnePlus 6 with this example ..."

Anyway, if someone has GPU experience, please chime in. If you know someone, you can show them the post or maybe boost :-).

#linuxphone#librem5
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