Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[Paul Moore]

Ever since v3.17 I've had a problem with displayport audio on my
system, but until lately I haven't had a chance to bisect the problem.
After a few rounds I've isolated the buggy commit to 0e32b39c
("drm/i915: add DP 1.2 MST support (v0.7)").

Simply put, prior to v3.17 everything worked correctly: audio from my
system was routed to my monitor via the DP connection and finally out
to the speakers connected to the monitor.  However, starting with
kernel v3.17 this no longer works.  The various PulseAudio tools all
indicate that the HDMI/DP audio output is unplugged/not-available.
I've tried a few different xrandr commands found via google and
manpages but nothing short of reverting to v3.16 solves the problem.
I'm hoping that someone with more understanding of the Intel graphics
drivers will be able to make some sense of it all and provide a fix.
I'm more than happy to provide additional information and test any
patches you may have.

For reference, my system is a ThinkPad T440s with a "Intel Corporation
Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
lspci) connected to a Dell U3011 via a Gefen DP KVM.

-Paul

-- 
paul moore
www.paul-moore.com

Re: Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[Paul Moore]

On Fri, Mar 13, 2015 at 11:19 PM, Paul Moore <paul@paul-moore.com> wrote:
> Ever since v3.17 I've had a problem with displayport audio on my
> system, but until lately I haven't had a chance to bisect the problem.
> After a few rounds I've isolated the buggy commit to 0e32b39c
> ("drm/i915: add DP 1.2 MST support (v0.7)").
>
> Simply put, prior to v3.17 everything worked correctly: audio from my
> system was routed to my monitor via the DP connection and finally out
> to the speakers connected to the monitor.  However, starting with
> kernel v3.17 this no longer works.  The various PulseAudio tools all
> indicate that the HDMI/DP audio output is unplugged/not-available.
> I've tried a few different xrandr commands found via google and
> manpages but nothing short of reverting to v3.16 solves the problem.
> I'm hoping that someone with more understanding of the Intel graphics
> drivers will be able to make some sense of it all and provide a fix.
> I'm more than happy to provide additional information and test any
> patches you may have.
>
> For reference, my system is a ThinkPad T440s with a "Intel Corporation
> Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
> lspci) connected to a Dell U3011 via a Gefen DP KVM.

Help?

The problem still exists on v4.0.1 and I know of at least one other
person that has reported the same problem.  As I said above, I'm
willing to do any additional debugging/testing needed, I just could
use some help on resolving this as I am definitely not a
X/graphics-driver expert.

-Paul

-- 
paul moore
www.paul-moore.com

Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[Jani Nikula]

On Fri, 08 May 2015, Paul Moore <paul@paul-moore.com> wrote:
> On Fri, Mar 13, 2015 at 11:19 PM, Paul Moore <paul@paul-moore.com> wrote:
>> Ever since v3.17 I've had a problem with displayport audio on my
>> system, but until lately I haven't had a chance to bisect the problem.
>> After a few rounds I've isolated the buggy commit to 0e32b39c
>> ("drm/i915: add DP 1.2 MST support (v0.7)").
>>
>> Simply put, prior to v3.17 everything worked correctly: audio from my
>> system was routed to my monitor via the DP connection and finally out
>> to the speakers connected to the monitor.  However, starting with
>> kernel v3.17 this no longer works.  The various PulseAudio tools all
>> indicate that the HDMI/DP audio output is unplugged/not-available.
>> I've tried a few different xrandr commands found via google and
>> manpages but nothing short of reverting to v3.16 solves the problem.
>> I'm hoping that someone with more understanding of the Intel graphics
>> drivers will be able to make some sense of it all and provide a fix.
>> I'm more than happy to provide additional information and test any
>> patches you may have.
>>
>> For reference, my system is a ThinkPad T440s with a "Intel Corporation
>> Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
>> lspci) connected to a Dell U3011 via a Gefen DP KVM.
>
> Help?
>
> The problem still exists on v4.0.1 and I know of at least one other
> person that has reported the same problem.  As I said above, I'm
> willing to do any additional debugging/testing needed, I just could
> use some help on resolving this as I am definitely not a
> X/graphics-driver expert.

Hmm, I never received your first mail.

Apparently audio on DP MST is problematic, and the debugging may get a
bit involved. Please file a bug at [1] so we don't clutter the lists
with logs etc. Please enable drm.debug=14 module parameter and attach
(to the bug) dmesg all the way from boot to trying audio on the monitor.

BR,
Jani.


>
> -Paul
>
> -- 
> paul moore
> www.paul-moore.com
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Jani Nikula, Intel Open Source Technology Center

Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[Jani Nikula]

On Mon, 11 May 2015, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Fri, 08 May 2015, Paul Moore <paul@paul-moore.com> wrote:
>> On Fri, Mar 13, 2015 at 11:19 PM, Paul Moore <paul@paul-moore.com> wrote:
>>> Ever since v3.17 I've had a problem with displayport audio on my
>>> system, but until lately I haven't had a chance to bisect the problem.
>>> After a few rounds I've isolated the buggy commit to 0e32b39c
>>> ("drm/i915: add DP 1.2 MST support (v0.7)").
>>>
>>> Simply put, prior to v3.17 everything worked correctly: audio from my
>>> system was routed to my monitor via the DP connection and finally out
>>> to the speakers connected to the monitor.  However, starting with
>>> kernel v3.17 this no longer works.  The various PulseAudio tools all
>>> indicate that the HDMI/DP audio output is unplugged/not-available.
>>> I've tried a few different xrandr commands found via google and
>>> manpages but nothing short of reverting to v3.16 solves the problem.
>>> I'm hoping that someone with more understanding of the Intel graphics
>>> drivers will be able to make some sense of it all and provide a fix.
>>> I'm more than happy to provide additional information and test any
>>> patches you may have.
>>>
>>> For reference, my system is a ThinkPad T440s with a "Intel Corporation
>>> Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
>>> lspci) connected to a Dell U3011 via a Gefen DP KVM.
>>
>> Help?
>>
>> The problem still exists on v4.0.1 and I know of at least one other
>> person that has reported the same problem.  As I said above, I'm
>> willing to do any additional debugging/testing needed, I just could
>> use some help on resolving this as I am definitely not a
>> X/graphics-driver expert.
>
> Hmm, I never received your first mail.
>
> Apparently audio on DP MST is problematic, and the debugging may get a
> bit involved. Please file a bug at [1] so we don't clutter the lists
> with logs etc. Please enable drm.debug=14 module parameter and attach
> (to the bug) dmesg all the way from boot to trying audio on the monitor.
>
> BR,
> Jani.

[1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI&component=DRM/Intel



>
>
>>
>> -Paul
>>
>> -- 
>> paul moore
>> www.paul-moore.com
>> _______________________________________________
>> Intel-gfx mailing list
>> Intel-gfx@lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> -- 
> Jani Nikula, Intel Open Source Technology Center

-- 
Jani Nikula, Intel Open Source Technology Center

Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[David Airlie]

----- Original Message -----
> From: "Jani Nikula" <jani.nikula@linux.intel.com>
> To: "Paul Moore" <paul@paul-moore.com>, "Dave Airlie" <airlied@redhat.com>, intel-gfx@lists.freedesktop.org
> Cc: "Daniel Gultsch" <daniel@gultsch.de>, linux-kernel@vger.kernel.org
> Sent: Monday, 11 May, 2015 6:01:49 PM
> Subject: Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s
> 
> On Mon, 11 May 2015, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> > On Fri, 08 May 2015, Paul Moore <paul@paul-moore.com> wrote:
> >> On Fri, Mar 13, 2015 at 11:19 PM, Paul Moore <paul@paul-moore.com> wrote:
> >>> Ever since v3.17 I've had a problem with displayport audio on my
> >>> system, but until lately I haven't had a chance to bisect the problem.
> >>> After a few rounds I've isolated the buggy commit to 0e32b39c
> >>> ("drm/i915: add DP 1.2 MST support (v0.7)").
> >>>
> >>> Simply put, prior to v3.17 everything worked correctly: audio from my
> >>> system was routed to my monitor via the DP connection and finally out
> >>> to the speakers connected to the monitor.  However, starting with
> >>> kernel v3.17 this no longer works.  The various PulseAudio tools all
> >>> indicate that the HDMI/DP audio output is unplugged/not-available.
> >>> I've tried a few different xrandr commands found via google and
> >>> manpages but nothing short of reverting to v3.16 solves the problem.
> >>> I'm hoping that someone with more understanding of the Intel graphics
> >>> drivers will be able to make some sense of it all and provide a fix.
> >>> I'm more than happy to provide additional information and test any
> >>> patches you may have.
> >>>
> >>> For reference, my system is a ThinkPad T440s with a "Intel Corporation
> >>> Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
> >>> lspci) connected to a Dell U3011 via a Gefen DP KVM.
> >>
> >> Help?
> >>
> >> The problem still exists on v4.0.1 and I know of at least one other
> >> person that has reported the same problem.  As I said above, I'm
> >> willing to do any additional debugging/testing needed, I just could
> >> use some help on resolving this as I am definitely not a
> >> X/graphics-driver expert.
> >
> > Hmm, I never received your first mail.
> >
> > Apparently audio on DP MST is problematic, and the debugging may get a
> > bit involved. Please file a bug at [1] so we don't clutter the lists
> > with logs etc. Please enable drm.debug=14 module parameter and attach
> > (to the bug) dmesg all the way from boot to trying audio on the monitor.
> >
>


I started looking at this today, the audio driver needs serious work to
make this happen, I'm trying to investigate how much work that is.

Dave.

Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST support (v0.7)") breaking DP audio on T440s

[Paul Moore]

On Monday, May 11, 2015 04:06:37 AM David Airlie wrote:
> ----- Original Message -----
> > From: "Jani Nikula" <jani.nikula@linux.intel.com>
> > To: "Paul Moore" <paul@paul-moore.com>, "Dave Airlie"
> > <airlied@redhat.com>, intel-gfx@lists.freedesktop.org Cc: "Daniel
> > Gultsch" <daniel@gultsch.de>, linux-kernel@vger.kernel.org Sent: Monday,
> > 11 May, 2015 6:01:49 PM
> > Subject: Re: [Intel-gfx] Commit 0e32b39c ("drm/i915: add DP 1.2 MST
> > support (v0.7)") breaking DP audio on T440s> 
> > On Mon, 11 May 2015, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> > > On Fri, 08 May 2015, Paul Moore <paul@paul-moore.com> wrote:
> > >> On Fri, Mar 13, 2015 at 11:19 PM, Paul Moore wrote:
> > >>> Ever since v3.17 I've had a problem with displayport audio on my
> > >>> system, but until lately I haven't had a chance to bisect the problem.
> > >>> After a few rounds I've isolated the buggy commit to 0e32b39c
> > >>> ("drm/i915: add DP 1.2 MST support (v0.7)").
> > >>> 
> > >>> Simply put, prior to v3.17 everything worked correctly: audio from my
> > >>> system was routed to my monitor via the DP connection and finally out
> > >>> to the speakers connected to the monitor.  However, starting with
> > >>> kernel v3.17 this no longer works.  The various PulseAudio tools all
> > >>> indicate that the HDMI/DP audio output is unplugged/not-available.
> > >>> I've tried a few different xrandr commands found via google and
> > >>> manpages but nothing short of reverting to v3.16 solves the problem.
> > >>> I'm hoping that someone with more understanding of the Intel graphics
> > >>> drivers will be able to make some sense of it all and provide a fix.
> > >>> I'm more than happy to provide additional information and test any
> > >>> patches you may have.
> > >>> 
> > >>> For reference, my system is a ThinkPad T440s with a "Intel Corporation
> > >>> Haswell-ULT Integrated Graphics Controller (rev 0b)" (according to
> > >>> lspci) connected to a Dell U3011 via a Gefen DP KVM.
> > >> 
> > >> Help?
> > >> 
> > >> The problem still exists on v4.0.1 and I know of at least one other
> > >> person that has reported the same problem.  As I said above, I'm
> > >> willing to do any additional debugging/testing needed, I just could
> > >> use some help on resolving this as I am definitely not a
> > >> X/graphics-driver expert.
> > > 
> > > Hmm, I never received your first mail.
> > > 
> > > Apparently audio on DP MST is problematic, and the debugging may get a
> > > bit involved. Please file a bug at [1] so we don't clutter the lists
> > > with logs etc. Please enable drm.debug=14 module parameter and attach
> > > (to the bug) dmesg all the way from boot to trying audio on the monitor.
> > >
>
> I started looking at this today, the audio driver needs serious work to
> make this happen, I'm trying to investigate how much work that is.

Hi Dave, Jani,

Thanks for take a look at this, I appreciate it.  It looks like the 
FreeDesktop BZ #89895 is the same problem I'm having so I added my information 
to that BZ.  Let me know if there is anything else I can do to help.

 * https://bugs.freedesktop.org/show_bug.cgi?id=89895

-Paul

-- 
paul moore
www.paul-moore.com