https://bugzilla.kernel.org/show_bug.cgi?id=74911
--- Comment #1 from Michel Dänzer michel@daenzer.net --- (In reply to Ivan Bulatovic from comment #0)
After booting 3.15.0-rc2 kernel, I can only see a message from grub indicating that kernel and initram images are loaded and that's it. No response from keyboard, I can only do a hard reset.
How long have you waited for? Trying to load a non-existent firmware file may only time out after a minute or so.
This makes sense, there is no radeon/PITCAIRN_mc2.bin blob anywhere. At least not in linux-firmware branch.
You can get it e.g. from:
http://people.freedesktop.org/~agd5f/radeon_ucode/
I have compiled radeon drivers into the kernel image itself, [...]
It's recommended to build the radeon driver as a module instead and let the firmware files be loaded from the initrd or normal filesystem.