KMS/radeon regression: failure to set modes on CEDAR & TAHITI; v3.11 vs 3.12-rc5/rc7

[Alex Deucher]

On Wed, Nov 6, 2013 at 7:12 PM, Robin H. Johnson <robbat2 at gentoo.org> wrote:
> On Wed, Nov 06, 2013 at 05:37:11PM -0500, Jerome Glisse wrote:
>> On Wed, Nov 06, 2013 at 05:48:55PM +0000, Robin H. Johnson wrote:
>> > On Wed, Nov 06, 2013 at 12:16:31PM -0500, Alex Deucher wrote:
>> > > On Wed, Nov 6, 2013 at 12:14 PM, Robin H. Johnson <robbat2 at gentoo.org> wrote:
>> > > > (Resending to dri-devel because the first one didn't make it).
>> > > >
>> > > > I apologize for not sending this sooner, but I wanted to be really sure that I
>> > > > wasn't introducing the bug elsewhere, and I was lacking time to even narrow it
>> > > > down this far.
>> > > >
>> > > > TL;DR:
>> > > > 3.11 kernel does proper modeset for dual 1920x1200 outputs
>> > > > 3.12-rc5/rc7 kernel fails to do proper modeset, blank screen after radeon loaded
>> > > Can you bisect?
>> > I have the next step in the bisect prepared (taking an educated guess
>> > and deciding that rc1 was probably also bad, because the changes after
>> > rc1 were minimal), but this is my primary box for getting work done; so
>> > I haven't rebooted since writing my email and preparing that next
>> > kernel.
>> Culprit likely d1e3b5564834ea24dee6b364a172365f64865fe5 try reverting that one.
> Confirmed as the buggy commit via bisect.
> Then reverted in 3.12 and 3.12 suddenly works.

I'm not sure how you would even be hitting those code paths as hw i2c
is disabled by default and I don't see it enabled on your kernel
command line.

Alex

>
> --
> Robin Hugh Johnson
> Gentoo Linux: Developer, Trustee & Infrastructure Lead
> E-Mail     : robbat2 at gentoo.org
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