Re: [Linux-fbdev-devel] Interface for detecting HSYNC / VSYNC

[James S. <jsi...@tr...>]

> I've got a video controller that can generate an interrupt when it's not
> refreshing the screen, so as to give the applications a chance to redraw
> without flicker.  What's the interface for this sort of thing.  I see
> several #defines for FB_SYNC_*, but I'm not sure how to use them.   I would
> think, send the process a signal, but that may be to slow.
> 
> Any good solutions?  What's current status quo?

   Really none. Their is a ioctl call but it is more report where the beam 
is. So you have to have the program basicly keep calling the ioctl
until something happens. Not very efficient.  
   What you could do is implement poll so you could do a select on the
fbdev file descriptor. 
   Note: You have to be careful with the console spinlock which disables
IRQs. While the console spinlock is held the interrupt will never trigger.
The HSYNC and VSYNC are for setting the card according to the monitors
abilities.