vc4: Detect working driver from cmdline

[Stefan Wahren]

> Eric Anholt <eric at anholt.net> hat am 21. Mai 2018 um 19:55 geschrieben:
> 
> 
> Stefan Wahren <stefan.wahren at i2se.com> writes:
> 
> > Hi,
> > in order to improve kernelci.org results and avoid false positive cases like this [1], i suggested to also test for a working VC4 driver. In order to keep it simple, we should do it from userspace.
> >
> > My first idea was:
> >
> > test -d /sys/kernel/debug/dri/0 || echo "Error case"
> >
> > But maybe you have a better / more reliable solution?
> >
> > [1] - https://storage.kernelci.org/mainline/master/v4.17-rc5-69-g3acf4e395260/arm64/defconfig/lab-mhart/boot-bcm2837-rpi-3-b.html
> 
> GL testing involves running piglit and comparing to a previous run to
> confirm no regressions, and we're building out the intel-gpu-tools
> support for display testing now.  That's what you'd need to make sure
> the driver actually works.  If you just want to make sure module probe
> doesn't fail, I guess that test is fine (it would catch bugs we've seen
> in the past).

AFAIK kernelci uses a initramfs, so adding much complexity isn't desired. I think module probe is sufficient and an improvement.