Hi, On 22 March 2016 at 08:50, Daniel Vetter <[email protected]> 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. Cheers, Daniel _______________________________________________ wayland-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/wayland-devel
