Hi, On 4 April 2017 at 11:27, Christopher James Halse Rogers <chris@xxxxxxxxxxxxxx> wrote: > On 4 April 2017 6:31:12 pm AEST, Daniel Vetter <daniel@xxxxxxxx> wrote: >>This seems like an awful specific special case. Why can't you do the >>entire dance upfront, i.e. import buffer, addfb2? None of that has any >>visible effect, and it will also allow you to check runtime constraints >>which can't be covered with this here. > > No, because addfb2 doesn't (or, rather, didn't) actually check any runtime constraints. > > The problem only appeared when the buffer is actually *used* in a modeset - otherwise I could do a (reasonably) cheap import/addfb/render on exporter/read out on importer dance to detect it. > > To be clear - this is trying to solve the problem “how can I tell if it's safe to addfb/pageflip rather than do a GL copy to a GPU-local buffer and flip from that?”. > > If I could guarantee that I'd only ever run on 4.13-or-later kernels (I think that's when the previous patches will land?), then this would indeed be mostly unnecessary. It would save me a bunch of addfb calls that would predictably fail, but they're cheap. Yeah, the ABI is that AddFB2 should fail hard on something which can never be used as a framebuffer. The fact it didn't is a bug rather than a behavioural change per se ... Cheers, Daniel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
