Re: [PATCH] Revert "drm/i915: fix infinite loop at gen6_update_ring_freq"

Daniel Vetter
2014-04-23T07:05:11Z

On Tue, Apr 22, 2014 at 06:25:12PM -0300, Paulo Zanoni wrote:
> 2014-04-11 6:02 GMT-03:00 Daniel Vetter <daniel@ffwll.ch>:
> > On Thu, Apr 10, 2014 at 10:52:26AM -0700, Ben Widawsky wrote:
> >> On Thu, Apr 10, 2014 at 10:50:43AM -0700, Ben Widawsky wrote:
> >> > On Thu, Apr 10, 2014 at 09:04:47AM +0200, Daniel Vetter wrote:
> >> > > This reverts commit 4b28a1f3ef55a3b0b68dbab1fe6dbaf18e186710.
> >> > >
> >> > > This patch duct-tapes over some issue in the current bdw rps patches
> >> > > which must wait with enabling rc6/rps until the very first batch has
> >> > > been submitted by userspace.
> >> > >
> >> > > But those patches aren't merged yet, and for upstream we need to have
> >> > > an in-kernel emission of the very first batch. I shouldn't have
> >> > > merged this patch so let's revert it again.
> >> >
> >> > I said this on the mailing last before you merged the patch.
> >>
> >> 20140402050338.GB13824@bwidawsk.net
> >
> > 20140402145813.GV7225@phenom.ffwll.local will explain things.
>
> There's now a regression report pointing to the revert:
> https://bugs.freedesktop.org/show_bug.cgi?id=77565 .
>
> What is the proposed solution now? Just WARN and still avoid the
> infinite loop? Or keep the infinite loop and leave the bug open?
> Disable BDW runtime PM?

I've thought that we can only hit this with the as-yet unmerged rc6
patches on bdw, so I'm really confused why this blows up now?

In any case I've thought Imre has stumbled over a similar issue on byt and
he has a fix to prevent runtime pm until the delayed rps init has run.
I've assigned the bug to him.

Still confused why this suddenly blew up ...
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch