Autofocus, Librem 5 -- need dma bufs? why?

[Robert Mader]

Hi Pavel,

the dmabuf allocation happens because the libcamera API guarantees that 
its buffers are dmabufs :/

Note that the usual dmabuf implementation used by recent distros like 
Fedora >= 41, pmOS >= 24.12 etc. is /dev/udmabuf. If your distro/kernel 
doesn't have that yet I'd actually suggest to update to something more 
modern or contact your distro maintainer.

Best regards,

Robert

On 26.03.25 21:32, Pavel Machek wrote:
> Hi!
>
> I'd like to record video on Librem 5. I do have code to turn bayer8
> into rgb888, and gstreamer can turn that into mkv video. "cam" can
> save bayer data to disk. So far so good.
>
> But AFAICT libcamera won't do auto exposure unless I request rgb888
> from it; at that point it pulls Software ISP in. I could use that if
> it was fast enough.
>
> But that wants to do DMA buffer allocations from /dev/dma_heap/*
> ... and I don't have that on the system. (And it really should not
> need them, as data end up on disk, not on GPU).
>
> Any ideas how to work around these? I guess stubbing out DMA buffer
> allocation would be easiest short-term solution, but...?
>
> Best regards,
> 								Pavel