The Coordinated Video Timings (CVT) is the latest standard approved by VESA
concerning video timings generation. It addresses the limitation of GTF which
is designed mainly for CRT displays. CRT's have a high blanking requirement
(as much as 25% of the horizontal frame length) which artificially increases
the pixelclock. Digital displays, on the other hand, needs to conserve the
pixelclock as much as possible. The GTF also does not take into account the
different aspect ratios in its calculation.
The new function added is fb_find_mode_cvt(). It is called by fb_find_mode()
if it recognizes a mode option string formatted for CVT. The format is:
<xres>x<yres>[M][R][-<bpp>][<at-sign><refresh>][i][m]
The 'M' tells the function to calculate using CVT. On it's own, it will
compute a timing for CRT displays at 60Hz. If the 'R' is specified, 'reduced
blanking' computation will be used, best for flatpanels. The 'i' and the 'm'
is for 'interlaced mode' and 'with margins' respectively.
To determine if CVT was used, check for dmesg for something like this:
CVT Mode - <pix>M<n>[-R], ie: .480M3-R (800x600 reduced blanking)
where: pix - product of xres and yres, in MB
M - is a CVT mode
n - the aspect ratio (3 - 4:3; 4 - 5:4; 9 - 16:9, 15:9; A - 16:10)
-R - reduced blanking
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This is a framebuffer driver for the Cyberblade/i1 graphics core.
Currently tridenfb claims to support the cyberblade/i1 graphics core. This
is of very limited truth. Even vesafb is faster and provides more working
modes and a much better quality of the video signal. There is a great
number of bugs in tridentfb ... but most often it is impossible to decide
if these bugs are real bugs or if fixing them for the cyberblade/i1 core
would break support for one of the other supported chips.
Tridentfb seems to be unmaintained,and documentation for most of the
supported chips is not available. So "fixing" cyberblade/i1 support inside
of tridentfb was not an option, it would have caused numerous
if(CYBERBLADEi1) else ... cases and would have rendered the code to be
almost unmaintainable.
A first version of this driver was published on 2005-07-31. A fix for a
bug reported by Jochen Hein was integrated as well as some changes
requested by Antonino A. Daplas.
A message has been added to tridentfb to inform current users of tridentfb
to switch to cyblafb if the cyberblade/i1 graphics core is detected.
This patch is one logical change, but because of the included documentation
it is bigger than 70kb. Therefore it is not sent to lkml and
linux-fbdev-devel,
Signed-off-by: Knut Petersen <Knut_Petersen@t-online.de>
Cc: Muli Ben-Yehuda <mulix@mulix.org>
Acked-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Add a small documentation of the driver parameters.
Signed-off-by: Sylvain Meyer <sylvain.meyer@worldonline.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Antonino A. Daplas