HDMI hotplug enable?

Alex Deucher alexdeucher at gmail.com
Wed Jun 13 09:18:25 PDT 2012

On Wed, Jun 13, 2012 at 12:04 PM, Greg G. <dargllun at googlemail.com> wrote:
> Hi Alex,
> On 13.06.2012 15:57, Alex Deucher wrote:
>> Hotplug should work fine.  The problem is the polling and hotplug
>> handling share the same common drm code, so I suspect disabling
>> polling has an adverse affect on hotplug events getting propagated to
>> userspace.  If you enable debugging in the drm (as root: echo 1>
>> /sys/module/drm/parameters/debug), you should see some HPD messages in
>> your kernel log when you plug/unplug.  If you see the messages, but
>> don't see any userspace events, then it's probably the problem I
>> described above.  Note that enabling debug when X is running will
>> probably generate more information than is useful, so I'd suggest
>> enabling it when X is not running (just the radeon kernel driver
>> loaded).
> Indeed: http://paste.ubuntu.com/1039275/
> So it is a bug, that poll=N inhibits propagating HPD events? Is this being
> worked on? Should I enter a bug report somehwere?

Wouldn't hurt to file a bug (https://bugs.freedesktop.org).  Daniel
Vetter has a set of patches that reworks the common hotplug handling
that may fix this:

>> Hotplug should work, and doesn't really have anything to do with hdmi
>> audio per se.  The gfx driver needs to get the information for the ELD
>> from the monitor via DDC, then pass it to the sound driver, at the
>> moment the radeon driver doesn't handle that.
> SeriousLy? No ELD for radeon? Sigh. Again - is this being worked on?

You need to load radeon with the audio parameter to enable hdmi audio
(e.g., radeon.audio=1 on the kernel command line in grub).  As for ELD
support, I'm not sure what's missing, I'm not really that familiar
with the audio side.


> Thanks
> Greg
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