On Tuesday, June 12, 2007 10:58:24 Keith Packard wrote:
> On Tue, 2007-06-12 at 19:23 +0200, Michel Dänzer wrote:
> > That would mean one register read sequence per waiter per interrupt
> > whereas otherwise it's one read sequence per CRTC (which is enabled
> > and has waiters) per interrupt. Looks like the latter can be made
> > to be more efficient.
>
> So, just so I understand the basic control flow:
>
> wait_for_vblank (crtc, seq)
> {
> enable_irq (crtc)
> while ((seq - crtc->current_seq) < 0)
> block ();
> disable_irq (crtc)
> }
>
> enable_irq (crtc)
> {
> if (enable_count++ == 0) {
> set_interrupts_enabled (crtc);
> crtc->current_seq = read_frame_count (crtc)
> }
> }
>
> disable_irq (crtc)
> {
> if (--enable_count == 0)
> set_interrupts_disabled (crtc);
> }
>
> irq ()
> {
> if (status & interrupt_crtc0)
> crtc0->current_seq = read_frame_count (crtc0);
> if (status & interrupt_crtc1)
> crtc1->current_seq = read_frame_count (crtc1);
> wakeup ();
> }
This looks good, but like Michel said, if only one pipe's vblank is
enabled, only the primary vblank counter should be updated (regardless
of *which* vblank count is enabled). But maybe that can be done at a
higher level, or maybe we can change that behavior and just make things
per-crtc as I've done with most of the code.
Jesse
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