1) Broadcom has quite a bit of stuff they want hidden and don't allow any of their many customers (including the Pi) to open-source.
2) The Pi 4's SoC has a hardware H.264 block and hardware H.265 block. Older Pi's had a hardware MPEG-2, hardware VC-1, and hardware H.264 block. These blocks require royalties and are _heavily_ protected by MPEG LA. If open-source software was released that could control these blocks, you could possibly expect a huge lawsuit against the Raspberry Pi Trading arm.
3) To the Pi's benefit, the VideoCore is not open-source but is the most openly-documented GPU available in a mobile device. Most Pi competitors use Mali, which if you look at Hackaday's Pine64 Un-Review, works with almost nothing and has wretched documentation. There is some open-source work, but quite a bit remains closed or completely inoperable on Linux.
4) If you need platform security, look elsewhere. The Pi doesn't support secure boot, licensed code signing requirements, and the new Pi 4 allows almost anyone to update the USB and SoC EEPROMs just by putting in a new SD card and running a few commands.
5) Cortex-A72 on Pi 4 is venerable to Spectre.
I think you're confusing copyright and patents. Just because some technology is patented, it doesn't mean it can't be open sourced.
Edit: Even if the RPT wrote their own firmware, not from Broadcom, and released it, they would still risk being sued to pieces for patent violations galore. After all, if you license H.265 alone, there are over 1,100+ pages in the Table of Contents alone just listing all of the patents worldwide on it.
Edit 2: And they could be possibly sued by Broadcom for violating the IP sharing agreement used for developing the chip by developing an open-source blob software.
If I buy your patented thing from you, that exhausts your patent rights for that copy of the thing. If I modify it, and do something you don’t like with it, you can’t come after me under patent law.
Note that I didn’t say anything about contract or copyright law—they may have signed something saying they wouldn’t reverse engineer the chip, or the sale could come with an end user Eula to that effect.
I'm just saying that if RPT tried to write their own firmware, they could be in big legal trouble, so I wouldn't expect any open-source firmware from RPT anytime soon.
It is “heavily protected” only in a legal sense, not a practical one.
1. The decoder blocks, H.264 and H.265, Broadcom/RPT can never release the source code to this without violating potentially thousands of patents worldwide.
2. The GPU of the Pi runs a ThreadX RTOS, which is licensed, runs on "billions" of devices worldwide, and can never be open-source without being sued for, well, huge amounts of damages. (The GPU blobs will never be open for this reason, but perhaps a mostly-complete GPU firmware NOT based on ThreadX will be released someday by the community, but I wouldn't hold my breath).
Also, you know the Pi's new OpenGL driver? All it does is convert the OpenGL commands and stuff into commands for this proprietary ThreadX GPU software.
3. If you think this isn't great, it's still better than the Pi's competitor boards, which have missing gaps in functionality, proprietary blobs which don't work well or even at all, and open-source implementations that currently just suck. (Read Hackaday's Pine64 Un-Review to see what I mean. It's improved a bit since then, but this is why "Pi-killers" haven't caught on.)
I use Pis as a stateless platform for an application that doesn’t use any graphics, GPU, or codecs. I imagine several other people do too.
You mean the old driver? The new one is based on Mesa.
I do know that The Raspberry Pi has a RTOS for the VideoCore GPU, and it is based on ThreadX RTOS, which is proprietary and used on "billions" of devices. The RPF will never be able to make that OSS.