So here are my thoughts:
1 - I never noticed this before, I wonder if it's a recent addition to the documentation.
2 -
--- Quote Start ---
I can't use the byte mask 1100, according to the above.
--- Quote End ---
Yes you can. According to the table, the only combinations you couldn't use would be:
0111
1011
1101
1110
0101
0110
1001
1010
3 - Have you tried it? Honestly I think I'd just try it anyway and see what happens. It may just work. It seems like if you always present a word address, the byte enables would be taken as they are given. I'd be surprised if there is actually some logic in the interconnect fabric that manipulates them. Try it.
4 - It does seem a little odd to me that you would be writing random bytes within a word. Especially pixel data. Are you sure you can't just buffer up multiple pixels and perform a single write. I guess I just don't know enough about what your trying to do to understand the usefulness.
Jake