Bug 71151

Hmm.

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 825853d..c459e4d 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -1756,6 +1756,8 @@ intel_sdvo_detect(struct drm_connector *connector, bool force)
                ret = connector_status_disconnected;
        else if (IS_TMDS(intel_sdvo_connector))
                ret = intel_sdvo_tmds_sink_detect(connector);
+       else if (IS_LVDS(intel_sdvo_connector))
+               ret = intel_sdvo->sdvo_lvds_fixed_mode ?  connector_status_connected : ret = connector_status_disconnected;
        else {
                struct edid *edid;

(In reply to Chris Wilson from comment #1)
> Hmm.
> 
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c


> +       else if (IS_LVDS(intel_sdvo_connector))
> +               ret = intel_sdvo->sdvo_lvds_fixed_mode ? 
> connector_status_connected : ret = connector_status_disconnected;

doesn't compile...

--> drivers/gpu/drm/i915/intel_sdvo.c:1740:78: error: lvalue required as left operand of assignment

have tried:
else if (IS_LVDS(intel_sdvo_connector))
   ret = intel_sdvo->sdvo_lvds_fixed_mode ? connector_status_connected : connector_status_disconnected;

doesn't work!

have hard set:

else if (IS_LVDS(intel_sdvo_connector))
    ret = connector_status_connected;


does work! ... ?

After fixing the typo, you also need:

diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
index 825853d..9b528a5 100644
--- a/drivers/gpu/drm/i915/intel_sdvo.c
+++ b/drivers/gpu/drm/i915/intel_sdvo.c
@@ -2622,6 +2622,7 @@ intel_sdvo_lvds_init(struct intel_sdvo *intel_sdvo, int device)
        if (!intel_sdvo_create_enhance_property(intel_sdvo, intel_sdvo_connector))
                goto err;
 
+       intel_sdvo_get_lvds_modes(connector);
        return true;
 
 err:

That should then be equivalent to always setting the LVDS as connected.

(In reply to Wilhelm Hagemeister from comment #2)
> have tried:
> else if (IS_LVDS(intel_sdvo_connector))
>    ret = intel_sdvo->sdvo_lvds_fixed_mode ? connector_status_connected :
> connector_status_disconnected;
> 
> doesn't work!

I'm thinking the problem is that we call .detect() before .get_modes(), so the first time around sdvo_lvds_fixed_mode isn't there yet.

(In reply to Chris Wilson from comment #3)
> After fixing the typo, you also need:
> 
>  
> +       intel_sdvo_get_lvds_modes(connector);
>         return true;
>  
>  err:
> 
> That should then be equivalent to always setting the LVDS as connected.

that works! Many thanks.

For the non-i915-expert: is this a workaround or a fix?

It is a fix for some assumptions we make through the LVDS detection and mode retrieval - in return it bakes in another assumption that the LVDS is connected for the lifetime of the driver. It's another fairly safe assumption - though boards do exist that may break it (but those tend to be hardware development boards, and we can document the workaround for our assumptions as they will affect only a very small minority).

Thank you for your testing.

Assigning to Chris for patch submission ...

Created attachment 128161 [details]
drm/i915/sdvo: Fix LVDS connector status detection

I think I've worked through all the associated issues here.

(In reply to Chris Wilson from comment #8)
> Created attachment 128161 [details]
> drm/i915/sdvo: Fix LVDS connector status detection
> 
> I think I've worked through all the associated issues here.

Wilhelm, please try Chris' patch on top of a recent kernel and report back.

(In reply to Jani Nikula from comment #9)
> (In reply to Chris Wilson from comment #8)
> > Created attachment 128161 [details]
> > drm/i915/sdvo: Fix LVDS connector status detection
> > 
> > I think I've worked through all the associated issues here.
> 
> Wilhelm, please try Chris' patch on top of a recent kernel and report back.

Jani, I don't have access to this machine right now, so it might take a while for the test and the report.

Resolved moved, we have another report at fdo bugzilla:
https://bugs.freedesktop.org/show_bug.cgi?id=63172

Wilhelm, we would still appreciate the testing of Chris' patch.

Created attachment 162761 [details]
kernel-trace after applying patch

(In reply to Jani Nikula from comment #11)
> Resolved moved, we have another report at fdo bugzilla:
> https://bugs.freedesktop.org/show_bug.cgi?id=63172
> 
> Wilhelm, we would still appreciate the testing of Chris' patch.

Jani,

I tested against a 3.14.12-rt9-2.44-desktop based on a vanilla kernel and patched with a PREEMPT-RT-Patch. This patch does NOT affect "intel_lvds.c".

I applied Chris' patch but that does not work. Find attached the kernel log.

I have this machine available another week and can do tests.

I am having the exact same problem on a gentoo-3.10.25 system. I tried the patch, but it did not work. 

Are there any further information about this?

Long time no updates (apart from Mike's comment #14 about v3.10). Closing.

If the problem persists with latest kernels, please file a bug at the freedesktop.org bugzilla [1], referencing this bug. Thank you.

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