[PATCH 5/7] compositor-drm: Gracefully handle vblank and flip invalid timestamps

Miguel Angel Vico mvicomoya at nvidia.com
Tue Mar 22 22:49:02 UTC 2016


On Tue, 22 Mar 2016 09:30:51 +0000
Daniel Stone <daniel at fooishbar.org> wrote:

> Hi,
> On 22 March 2016 at 08:50, Daniel Vetter <daniel at ffwll.ch> wrote:
> > On Tue, Mar 22, 2016 at 08:47:12AM +0000, Daniel Stone wrote:  
> >> This is odd. Instant queries failing is fine, but in which
> >> circumstances can you fail to return a valid timestamp in a
> >> pageflip event ... ? I don't know of any other kernel driver which
> >> does this - at the very least, if you don't have a hardware
> >> timestamp, then you log the time in your kernel driver which
> >> handles the hardware event (e.g. softirq handler), and use that
> >> instead.  
> >
> > nouveau bugs iirc. Yes, should never happen, it's a bug in the
> > kernel driver that iirc Mario recently tracked down. nouveau
> > somehow started the vblank machinery before the pipe was up, or
> > something like that.
> >
> > So yeah happens, I'm not sure we want to let kernel drivers get
> > away with plain broken behavior forever. I'm leaning towards nack,
> > pls fix the kernel driver.  
> Yes, particularly as no-one has reported it on any other drivers. I
> don't think it's behaviour we really want to support.
> > And maybe make sure the corresponding igt pass ;-)  
> For reference, igt here is intel-gpu-tools, which despite its name is
> actually a generic KMS test/conformance suite. Most of the tests are
> still Intel-specific, but we are actively working on making them
> generic - I was actually in the middle of reviewing a patchset to make
> a rather larger chunk of it generic when I got distracted by this
> thread. ;) It's a great way to find out ways in which your driver
> breaks userspace expectations of a 'well-behaved' KMS driver early.

Thanks guys! We'll fix this in our driver and remove the workaround in

> Cheers,
> Daniel


NVIDIA GmbH, Wuerselen, Germany, Amtsgericht Aachen, HRB 8361
Managing Director: Karen Theresa Burns

This email message is for the sole use of the intended recipient(s) and may contain
confidential information.  Any unauthorized review, use, disclosure or distribution
is prohibited.  If you are not the intended recipient, please contact the sender by
reply email and destroy all copies of the original message.

More information about the wayland-devel mailing list