[Intel-gfx] Intel-gfx Digest, Vol 57, Issue 7

[Daniel Vetter]

On Tue, Oct 2, 2012 at 7:45 PM, Mario Kleiner
<mario.kleiner at tuebingen.mpg.de> wrote:
>
> I'm fine with removing the hack and fixing this properly, especially if you
> say that it didn't work realiably in some cases. But i hope this means that
> timestamping sanity tests via flip_test are a part of your regular QA
> testing before you release a new kms driver, so bugs get caught pre-release?

Running i-g-t tests is part of our nightly testrun. If you add in the
machines Chris&me have we pretty much cover every platform ever
shipped by Intel ;-)

> Otherwise many scientists would get pretty nervous when using Intel gpus in
> the future.

... so I hope your scientists won't get nervous ;-) I still have a few
things I need to add to the flip test though:
- interactions with wait_vblank (both the blocking version and the
event version)
- checking whether the timestamps are accurately space (since we can
at least read out the line counter, we should be far accurater that 1%
there).
- if you have any ideas for further test, their' highly welcome. One
thing we unfortunately can't really test is whether the timestamp is
really when the hw starts scanning out the first line of the new
frame. But extremely low jitter and whether we pick the right frame
(or accidentally overcorrect by an entire frame like this code
sometimes managed to do) should able be covered.

Eventually I want to also get rid of the delayed vblank disabling and
make the frame counter readout race-free (we probably need to move a
bit of drm core logic into the driver for that). Again, I'll only
merge patches once I'm happy with the evilness of the tests ...

> Btw. if you remove the hack in the followup patch, you can also remove the
> do_gettimeofday(&tnow).

Indeed, thanks for spotting this. I'll resend v2 of this patch.

Yours, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch