fbdev: s3fb: Implement 1 and 2 BPP modes, improve 4 BPP

With the right setup S3 cards can display 1 and 2 BPP packed pixel
modes, even in high resolutions. So this patch makes them available.

The 4 BPP packed pixel mode had one pixel column of garbage on the
left side due to how the shift register works, this is fixed now.

There was a limitation that only 8 pixel wide fonts could be used at 4
BPP. Since the CFB routines were updated to handle reverse pixel
ordering correctly that limitation doesn't exists and was removed now.

In 4 BPP interleaved planes mode font widths of multiply of 8 are
accepted now, not just 8 pixels.

The horizontal screen position will not move as much between modes as it
used to. That was caused by the various amount of pipeline delay which
is compensated now as much as possible.

While adjusting the code direct port access of PEL registers was
corrected. Should work now on systems where these are memory mapped.

I've noticed that when in 1 BPP mode the console is used with Unicode
fonts erasing might be done with non-blanks. That's a bug in the VT code
and so not part of this patch.

Signed-off-by: Zsolt Kajtar <soci@c64.rulez.org>
Signed-off-by: Helge Deller <deller@gmx.de>

0 files changed, 0 insertions, 0 deletions