Re: Vertical retrace interrupts?

On Sat, 2003-02-01 at 05:32, Sven Luther wrote:

On Fri, Jan 31, 2003 at 08:12:16PM +0100, Michel Dänzer wrote:

quoted

On Fre, 2003-01-31 at 19:35, Antonino Daplas wrote:

quoted

On Fri, 2003-01-31 at 19:24, Michel Dänzer wrote:

quoted

You don't need X to use the DRM, just some privileged client to
initialize it.

You're right.  I just realized that since DRM already has an interrupt
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.

So, how about this?  Let fbdev have its own vblank ioctl, but for fbdev
drivers with a DRM counterpart, fbdev will just call the DRM
wait_vblank() and send_vbl_signals() functions.   Do you think this is
doable, I haven't examined the code thoroughly?  

The main goal is too avoid having 2 independent interrupt handlers for
one device.

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?

The fbdev driver will automatically load the DRM module when it refers
to any exportable symbol of DRM.  We can also make the fbdev drivers
specifically depend on DRM in Kconfig so users don't accidentally
compile fbdev without its DRM counterpart.

The aim is not to avoid code duplication, although that is a plus, it's
two independent handlers clashing and locking up the machine.

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.

I was wondering about this to.  How much initialization is required?  Is
it not enough to just load the DRM module?

Also, we have fbdev drivers that are incompatible with DRM, so having
fbdev load DRM is like telling it to commit suicide :-)

Tony




-------------------------------------------------------
This SF.NET email is sponsored by:
SourceForge Enterprise Edition + IBM + LinuxWorld = Something 2 See!
http://www.vasoftware.com