Le dimanche 15 octobre 2017 à 23:40 +0300, Sakari Ailus a écrit : > Hi Nicolas, > > On Tue, Oct 10, 2017 at 11:40:10AM -0400, Nicolas Dufresne wrote: > > Le mardi 29 août 2017 à 14:26 +0300, Stanimir Varbanov a écrit : > > > Currently videobuf2-dma-sg checks for dma direction for > > > every single page and videobuf2-dc lacks any dma direction > > > checks and calls set_page_dirty_lock unconditionally. > > > > > > Thus unify and align the invocations of set_page_dirty_lock > > > for videobuf2-dc, videobuf2-sg memory allocators with > > > videobuf2-vmalloc, i.e. the pattern used in vmalloc has been > > > copied to dc and dma-sg. > > > > Just before we go too far in "doing like vmalloc", I would like to > > share this small video that display coherency issues when rendering > > vmalloc backed DMABuf over various KMS/DRM driver. I can reproduce > > this > > easily with Intel and MSM display drivers using UVC or Vivid as > > source. > > > > The following is an HDMI capture of the following GStreamer > > pipeline > > running on Dragonboard 410c. > > > > gst-launch-1.0 -v v4l2src device=/dev/video2 ! video/x- > > raw,format=NV16,width=1280,height=720 ! kmssink > > https://people.collabora.com/~nicolas/vmalloc-issue.mov > > > > Feedback on this issue would be more then welcome. It's not clear > > to me > > who's bug is this (v4l2, drm or iommu). The software is unlikely to > > be > > blamed as this same pipeline works fine with non-vmalloc based > > sources. > > Could you elaborate this a little bit more? Which Intel CPU do you > have > there? I have tested with Skylake and Ivy Bridge and on Dragonboard 410c (Qualcomm APQ8016 SoC) (same visual artefact) > > Where are the buffers allocated for this GStreamer pipeline, is it > v4l2src > or another element or somewhere else? This is from V4L2 capture driver, exported as DMABuf, drivers are UVC and VIVID, both are using the vmalloc allocator. Nicolas
