Re: VESAFB CUSTOM RESOLUTION

["Antonino A. Daplas" <adaplas@gmail.com>]

On Wed, 2007-07-18 at 16:45 +0300, Al Boldi wrote:
> Antonino A. Daplas wrote:
> > On Wed, 2007-07-18 at 13:42 +0300, Al Boldi wrote:
> > > Geert Uytterhoeven wrote:
> > > > On Wed, 18 Jul 2007, Sasa Ostrouska wrote:
> > >
> > > Is there any technical reason why vesafb shouldn't support non-BIOS
> > > modes?
> >
> > vesafb can only use modes included by the vendor in the card's BIOS. The
> > mode table contains standard modes defined by VESA, and perhaps
> > vendor-defined custom modes. However, the mode ID of custom modes varies
> > from card to card, so you have to 'probe' the BIOS first for the list of
> > modes and their associated ID.  X + the 'vesa' driver does that probe,
> > and so does the lrmi tool vbetest.
> >
> > So, one cannot just set any mode, unless that mode is already defined in
> > the BIOS mode table. In VBE 3.0, you might be able to choose an
> > arbitrary vertical refresh rate, but that's the best mode tuning you can
> > do with the video BIOS.
> 
> Thanks for a great explanation!
> 
> Looks like this chip supports VBE 3.0, but it only locks into 60Hz refresh.  
> Here is an excerpt; full log attached.
> 
> 

What you need to look at the X log is this particular part (this is the
output of my card, and for the sake of brevity, I removed the
descriptive sections):

Mode: 100 (640x400)
Mode: 101 (640x480)
Mode: 102 (800x600)
Mode: 103 (800x600)
Mode: 104 (1024x768)
Mode: 105 (1024x768)
Mode: 106 (1280x1024)
Mode: 107 (1280x1024)
*Mode: 10e (320x200)
Mode: 10f (320x200)
*Mode: 111 (640x480)
Mode: 112 (640x480)
*Mode: 114 (800x600)
Mode: 115 (800x600)
*Mode: 117 (1024x768)
Mode: 118 (1024x768)
Mode: 11a (1280x1024)
Mode: 11b (1280x1024)
Mode: 130 (320x200)
Mode: 131 (320x400)
*Mode: 132 (320x400)
Mode: 133 (320x400)
Mode: 134 (320x240)
*Mode: 135 (320x240)
Mode: 136 (320x240)
*Mode: 13d (640x400)
Mode: 13e (640x400)
Mode: 145 (1600x1200)
Mode: 146 (1600x1200)
Mode: 147 (1400x1050)
Mode: 148 (1400x1050)
Mode: 152 (2048x1536)

The list of modes include standard VESA modes and custom modes such as
2048x1536.  So, if I want to use this mode for vesafb, I will add
vga=0x352 (0x152 + 0x200) to my boot line.

Tony

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