Re: framebuffer corruption due to overlapping stp instructions on arm64

[Mikulas Patocka <mpatocka@redhat.com>]

On Mon, 6 Aug 2018, Ard Biesheuvel wrote:

> No that works fine for me. VDPAU acceleration works as well, but it
> depends on your chromium build whether it can actually use it, I
> think? In any case, mplayer can use vdpau to play 1080p h264 without
> breaking a sweat on this system.

I didn't install the vdpau libraries and firmware. mplayer plays through 
xv and works (it can't play through vdpau). Chromium uses 
I-don't-know-what and locks up.

> Note that the VDPAU driver also relies on memory semantics, i.e., it
> may use DC ZVA (zero cacheline) instructions which are not permitted
> on device mappings. This is probably just glibc's memset() being
> invoked, but I remember hitting this on another PCIe-impaired arm64
> system with Synopsys PCIe IP

> Are you setting the pstate to auto? That helps a lot in my experience.
>
> I.e.,
>
> echo auto > /sys/kernel/debug/dri/0/pstate

I tried that, but it didn't help.

Mikulas