Probably You missed my posts about chmod. App creates file descriptor with RW flag (but it doesnt write into that file). In my case 444 was working, but in case of @Randy222 it wasnt. As far as I remeber, changing 444 to 666 (2 = write permission) worked for him.
In other words do:
chmod 666 /dev/hdcode_gpio
Instead of:
chmod 444 /dev/hdcode_gpio
Yes, 444 no good. 666 is good.
But I noted, on my 804 (probably for all 800's), HW-12 to HW-8 (via software) does not appear to enrich the product. I also run my 804 with the 914 vendor.bin and some lics.
Didn't you mention the hdcode KLM was being called by other processes so not really sure what the impact is when disabling that KLM?
It might be a prudent test to mod that ko KLM so that it perhaps reads a user file that logical maps the gpio pin names to a value, this way you can just plop 0 or 1 into a file and reload the KLM. This would bypass actual read to the RK, etc.
We must remember that the 900 has a bunch more hardware inside.
We could probably carve out a hack thread for 800, and one for 900, but this thread is long and very mixed already.