Re: [Linux-fbdev-devel] [PATCH]: EDID parser

Petr Vandrovec
2003-04-03T09:54:17Z

On 3 Apr 03 at 9:40, Sven Luther wrote:
> On Thu, Apr 03, 2003 at 03:07:33AM +0100, Petr Vandrovec wrote:
> > On 2 Apr 03 at 22:55, James Simmons wrote:
> >
> > > It doesn't need a struct pci_dev in this case. It is possible to get this
> > > info from the i2c bus but I never seen any drivers do this. What data would
> > > we have to pass in get the EDID inforamtion? So the question is how
> > > generic will get_EDID end up being or will we have to have driver specfic
> > > hooks since I don't pitcure i2c approaches being the same for each video
> > > card. Petr didn't you attempt this with the matrox driver at one time?
> >
> > Yes, matroxfb provides one i2c (DDC) bus for each output videocard has.
> > I ended with only this support (and userspace EDID parser) as i2c was
> > initialized loong after framebuffer at that time... Now when i2c is usable
> > when fbdev initializes, it looks much better.
> >
> > Only get_EDID interface I need is one which gets i2c bus as argument. But
> > I have no idea how I should handle situation where you have connected
> > two different monitors to both crtc1 outputs... Like 50Hz PAL TV &
> > 60+Hz VGA monitor. Currently it is user responsibility to resolve such
> > situation...
>
> Is the EDID reading stuff not done per head ?

No. With matroxfb, you have two framebuffer devices, /dev/fb0 & /dev/fb1,
which can be connected to any of three outputs: analog primary, analog
secondary and DVI. Analog primary & DVI share same pair of DDC cables,
and analog secondary has its own... And user can interconnect fb* with
outputs in almost any way he wants, as long as hardware supports it.
Petr Vandrovec