[igt-dev] [PATCH i-g-t] igt/tests/kms_dp_tiled_display.c : kms test file for display port tiled displays

[Ser, Simon]

On Wed, 2019-08-07 at 18:10 -0700, Tolakanahalli Pradeep, Madhumitha wrote:
> > > I believe tests in kms_flip do a similar check. The
> > > page_flip_handler
> > > function handles the page flip event (which is given the flip
> > > timestamp
> > > and sequence number). check_state verifies that the timestamp is
> > > close
> > > enough to what we expect (in our atomic check, maybe we can compare
> > > with strict equality).
> > > 
> > > Since we're dealing with multiple CRTCs, it may be a good idea to
> > > use
> > > drmEventContext.version = 3 with page_flip_handler2 so that we also
> > > get
> > > the CRTC in the page flip handler. Version 3 is a core DRM feature,
> > > all
> > > drivers support it given a recent enough kernel.
> > > 
> > > Rough pseudo-code:
> > > 
> > > 	/* When committing buffer, request a page flip */
> > > 	drmModeAtomicCommit(fd, req, DRM_MODE_ATOMIC_NONBLOCK |
> > > 			    DRM_MODE_PAGE_FLIP_EVENT, data);
> > 
> > Here we do the modese with igt_display_commit2 call that then calls
> > drmModeAtomicCommit but
> > doesnt call it with Page flip, do we have another igt helper that
> > does a atomic commit with
> > page flip event?
> > 
> > Can we not just do atomic commit and get vblank events so for two
> > crtcs we get two events and compare
> > the timestamp and make sure they are close enough?

I believe doing an atomic commit with DRM_MODE_PAGE_FLIP_EVENT as
Madhumitha suggested should be enough.

> > Manasi
> > 
> > > 	static void page_flip_handler(int fd, unsigned seq,
> > > 				      unsigned tv_sec,
> > > 				      unsigned tv_usec,
> > > 				      unsigned crtc_id, void *data)
> > > 	{
> > > 		/* Compare params with the other page flip */
> > > 	}
> > > 
> > > 	/* When we get POLLIN in the DRM FD */
> > > 	drmEventContext event = {
> > > 		.version = 3,
> > > 		.page_flip_handler2 = page_flip_handler,
> > > 	};
> > > 	drmHandleEvent(fd, &event);
> > > 
> 
> I was trying to implement the above code with igt_display_commit2.
> Looks like I'm timing out while poll-ing for POLLIN.
> 
> Is there something I could be doing wrong? According to my
> understanding, igt_display_commit2 should cause a page-flip event
> right?

Hmm. Yeah, it should work, assuming you use DRM_MODE_PAGE_FLIP_EVENT
when doing the atomic commit. Can you push your code somewhere (e.g. on
a GitLab fork) so that I can have a look?