lkml.org 
[lkml]   [2017]   [Oct]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] media: vb2: unify calling of set_page_dirty_lock
From
Date
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

\
 
 \ /
  Last update: 2017-10-16 01:09    [W:0.074 / U:0.012 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site