Hello Sam,
On 2/23/22 21:25, Sam Ravnborg wrote:
[snip]
>
> Question: What is cfb an abbreviation for anyway?
> Not related to the patch - but if I have known the memory is lost..
>
I was curious so I dug on this. It seems CFB stands for Color Frame Buffer.
Doing a `git grep "(CFB)"` in the linux history repo [0], I get this:
Documentation/isdn/README.diversion: (CFB).
drivers/video/pmag-ba-fb.c: * PMAG-BA TURBOchannel Color Frame Buffer (CFB) card support,
include/video/pmag-ba-fb.h: * TURBOchannel PMAG-BA Color Frame Buffer (CFB) card support,
Probably the helpers are called like this because they were for any fbdev
driver but assumed that the framebuffer was always in I/O memory. Later some
drivers were allocating the framebuffer in system memory and still using the
helpers, that were using I/O memory accessors and it's ilegal on some arches.
So the sys_* variants where introduced by commit 68648ed1f58d ("fbdev: add
drawing functions for framebuffers in system RAM") to fix this. The old
ones just kept their name, but probably it should had been renamed to io_*
for the naming to be consistent with the sys_* functions.
[0]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/
Best regards,
--
Javier Martinez Canillas
Linux Engineering
Red Hat
