Hardware Decoding Library: HEVC support

I have trouble executing HEVC hardware decoding while H264 hardware decoding is working fine following the instructions found here:
https://docs.khadas.com/vim3/HowToUseHardwareDecodingLibrary.html

To be honest the provided example did not report any case with HEVC decoding, just only H.264 and MPEG4.
Following the example found on the master branch it has been easy to support even the HEVC decoding:

vpcodec->has_video = 1;
if (_codec == “h264”) {
spdlog::get(_name)->info(“Video codec H.264”);
vpcodec->video_type = VFORMAT_H264;
vpcodec->am_sysinfo.format = VIDEO_DEC_FORMAT_H264;
vpcodec->am_sysinfo.param = (void *)(EXTERNAL_PTS | SYNC_OUTSIDE);
} else if (_codec == “h265”) {
spdlog::get(_name)->info(“Video codec H.265”);
vpcodec->video_type = VFORMAT_HEVC;
vpcodec->am_sysinfo.format = VIDEO_DEC_FORMAT_HEVC;
vpcodec->am_sysinfo.param = (void *) (EXTERNAL_PTS | SYNC_OUTSIDE);
} else {
spdlog::get(_name)->critical(“Codec not available: {}”, _codec);
return;
}
vpcodec->stream_type = STREAM_TYPE_ES_VIDEO;
vpcodec->am_sysinfo.rate = 96000 / _fps;
vpcodec->am_sysinfo.height = _h;
vpcodec->am_sysinfo.width = _w;
vpcodec->has_audio = 0;
vpcodec->noblock = 0;

I noticed that sometimes the HEVC decoding attempt blocks the whole cpu, while sometimes returns just vertical lines.
I’ve set the output format to V4L2_PIX_FMT_BGR24, and the stream resolution is 1080p.

So I doubt HEVC is currenlty completely supported by the library.
Is it true?