Re: [Linux-fbdev-devel] Vertical retrace interrupts?

[Sven L. <lu...@dp...>]

On Fri, Jan 31, 2003 at 08:12:16PM +0100, Michel D=E4nzer wrote:
> On Fre, 2003-01-31 at 19:35, Antonino Daplas wrote:
> > On Fri, 2003-01-31 at 19:24, Michel D=E4nzer wrote:
> > >=20
> > > You don't need X to use the DRM, just some privileged client to
> > > initialize it.
> >=20
> > You're right.  I just realized that since DRM already has an interrup=
t
> > handler, it is unwise for fbdev to install its own interrupt handler
> > too, as this will fatally lock up the machine when DRM and fbdev are
> > loaded simultaneously.
> >=20
> > So, how about this?  Let fbdev have its own vblank ioctl, but for fbd=
ev
> > drivers with a DRM counterpart, fbdev will just call the DRM
> > wait_vblank() and send_vbl_signals() functions.   Do you think this i=
s
> > doable, I haven't examined the code thoroughly? =20
> >=20
> > The main goal is too avoid having 2 independent interrupt handlers fo=
r
> > one device.
>=20
> A noble goal, but the framebuffer device would still need its own code
> when the DRM isn't active, so I'm afraid there's no way around code
> duplication, unless we could somehow factor out the common code for the
> two to share?

Could it not be that the fbdev sort of minimally intialize the DRM when
it is not already active ? After all, the fbdev knows as much, if not
more, than the X driver about the graphic chips state, especially if the
X driver is using the fbdev.

Friendly,

Sven Luther