Hi Lucas,
On Fri, 27 May 2016 14:23:02 +0200 Lukas Wunner wrote:
> Hi Bruno,
>
> Wilfried Klaebe has reported a deadlock in 4.6 which he bisected to
> my commit 704ab614ec12 ("drm/i915: Defer probe if gmux is present but
> its driver isn't"), but which is ultimately caused by your commit
> 4eebd5a4e726 ("apple-gmux: lock iGP IO to protect from vgaarb changes").
>
> What's happening is that your commit calls vga_tryget() in apple-gmux,
> which succeeds. When Xorg is launched, it opens /dev/vga_arbiter and
> calls vga_get(), which deadlocks. See the attachments to this bugzilla
> entry, in particular the stacktrace at the end of "kern.log / dmesg of
> non-working Linux 4.6.0":
> https://bugzilla.kernel.org/show_bug.cgi?id=88861#c11
> https://bugzilla.kernel.org/attachment.cgi?id=217541
Looks like here the two GPUs are visible and the right one is being
selected.
So your patch to allow including ISA devices in vga arbitration would
not change anything here.
Is it known at what time the lockup happens?
