temp/libcamera: Use udmabuf by default

Depends on !5584 (merged), !5585 (merged) and !5586 (merged)

udmabufs appears to be the better solution for buffer allocation than CMA heaps and distros like Fedora will use them by default for the libcamera swISP. Notably systemd 257 will allow users to use them by default.

They use "normal" memory allocation which has several benefits:

1. No "reservation" required, thus no size limit and no blocking of memory.
2. Allocation size is properly attributed, cgroup limits are enforced etc.

The big disadvantage is that they require GPUs to have IOMMUs in order to be able to import buffers without copy. This is the case for all more modern devices - such as (most|all)? qcom ones, but some older ones from the GLES 2.0 era might not have it. Crucially we need to check:

• Librem5 - works
• PinePhone - works

and keep CMA enabled there.

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Notes:

• udmabuf support was added to libcamera 0.3.1 following upstream discussion.
• sdm670 and sdm845 already ship with udmabuf enabled but could now disable CMA reservation

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See also:

1. https://gitlab.com/postmarketOS/pmbootstrap/-/issues/2174#note_2081391111
2. !5399 (comment 2077524825)

added 3 commits

• d3a87135 - linux-purism-librem5: enable CONFIG_UDMABUF
• 3ae314ed - linux-postmarketos-allwinner: enable CONFIG_UDMABUF
• 27385c81 - temp/libcamera: Add udev rule with uaccess tag for udmabuf

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By Robert Mader on 2024-08-29T16:58:11

added 3 commits

• 70d7c7a9 - linux-purism-librem5: enable CONFIG_UDMABUF
• 2ff22eab - linux-postmarketos-allwinner: enable CONFIG_UDMABUF
• a1ffb585 - temp/libcamera: Add udev rule with uaccess tag for udmabuf

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By Robert Mader on 2024-08-29T17:16:19

changed the description

By Robert Mader on 2024-08-29T17:19:57

changed the description

By Robert Mader on 2024-08-29T17:20:27

changed the description

By Robert Mader on 2024-08-29T17:27:32

changed the description

By Robert Mader on 2024-08-29T19:17:19

added 3 commits

• 9c6646c8 - temp/libcamera: Change udev rule with uaccess tag for udmabuf
• 3e78b388 - linux-purism-librem5: enable CONFIG_UDMABUF
• 19b9b1e7 - linux-postmarketos-allwinner: enable CONFIG_UDMABUF

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By Robert Mader on 2024-08-29T19:42:06

added 5 commits

• 19b9b1e7...8ce102b6 - 2 commits from branch postmarketOS:master
• cc0d22f3 - temp/libcamera: Change udev rule with uaccess tag for udmabuf
• 57aeebf4 - linux-purism-librem5: enable CONFIG_UDMABUF
• 0c1f7033 - linux-postmarketos-allwinner: enable CONFIG_UDMABUF

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By Robert Mader on 2024-08-29T19:42:24

Turns out even the Librem5 and PinePhone work just fine with udmabuf - including direct import with EGL[1] \o/

So it looks like we can switch to udmabuf for all currently supported devices (that have working camera support).

cc @pabloyoyoista

1: tested with Gstreamer glupload and waylandsink

By Robert Mader on 2024-08-31T18:38:50

marked this merge request as ready

By Robert Mader on 2024-08-29T19:45:21

changed the description

By Robert Mader on 2024-08-29T19:45:29

mentioned in issue pmbootstrap#2174 (closed)

By Robert Mader on 2024-08-29T19:54:53

changed the description

By Robert Mader on 2024-08-29T20:39:09

changed the description

By Robert Mader on 2024-08-29T20:41:01

added camera type::feature labels

Please modify kconfigcheck.toml with the things we now need for the libcamera option. This warranties every kernel will have this enabled in the future if in use with libcamera

By Pablo Correa Gomez on 2024-08-29T21:45:52

So cool to see this continuing moving forward at the speed of light!

By Pablo Correa Gomez on 2024-08-30T06:50:39

added 1 commit

• 8d627079 - kconfigcheck: Add udmabuf instead of cma heaps for libcamera

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By Robert Mader on 2024-08-29T21:45:41

added 1 commit

• 7d4d5ca6 - kconfigcheck: Add udmabuf instead of cma heaps for libcamera

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By Robert Mader on 2024-08-29T21:48:27