Bug#226973: xserver-xfree86: [glint] second card at wrong resolution

[Sven Luther <sven.luther@wanadoo.fr>]

On Tue, Mar 30, 2004 at 06:02:03PM -0500, Clint Adams wrote:
> > I believe that the cloack is different for 8bpp and 16 or 24 bpp, don't
> > remember exactly. At 8bpp, the max clock range is 230Mhz in the driver i
> > think. You looked at it, you have the hardware, you just have become the
> > resident expert on this issue :).
> 
> Ahh.  I tried increasing the 32bpp number to 150MHz, and was successfully
> able to use a mode at 135MHz.  I am confused as to why the Pixmap setting
> affects the ramdac frequency.  Is this a mistake or am I misunderstanding 
> something?  Would it be okay to set the maximum based on depth instead
> of bitsPerPixel, or is bitsPerPixel wrong if it's set to 32 at a plain
> 24-bit depth?

I would have to look in the specs, but i believe the ramdac is only able
to push less pixels if those are of 16 or 32 bpp. This is the case for
all 3Dlabs chips prior to the permedia3. Look at the part in glint_driver.c
where these values are set. I have no explanation also, since my
involvement was with the permedia3, so maybe ask Alan Hourihane about
it.

Friendly,

Sven Luther