I learned in this post that the OpenCL support can be found in AOSP for db410c? Is it true also for db820c?
No.
There are no AOSP releases for DB820C based on the vendor driver set. Note also that OpenCL support for DB410C is only available in the AOSP releases that based on the vendor driver set and these are getting rather old (lollipop and marshmallow). Any newer AOSP builds for DB410C will not have OpenCL support.
I don’t know what the exact status is, but OpenCL will be provided for the Qualcomm Adreno GPUs (i.e., all of the “dragonboard’s” – 410, 820, 845) via mesa/gallium3d/clover.
Mesa is apparently receiving patches related to this regularly;
https://cgit.freedesktop.org/mesa/mesa/log/?qt=grep&q=clover
And also note that AOSP’s mesa is not necessarily all the way up to date.
https://android.googlesource.com/platform/external/mesa3d/+log/refs/heads/master
Currently its at mesa 20.0.1, so some of the newer commits won’t be present.
https://android.googlesource.com/platform/external/mesa3d/+/refs/heads/master/VERSION
And to clarify the 410c OpenCL situation… its not actually AOSP where OpenCL is supported. Its in the ancient Qualcomm fork of AOSP (5.1), which uses their proprietary closed source drivers. AOSP has NEVER supported OpenCL in ANY dragonboard.
