On 02/24/2016 10:53 PM, Jindal, Sonika wrote:

Hi Joe,

Yes, first thing to try is to increase the tries.

We testing with 300 retries, but the second monitor still did not show up. However, it did show up in lspci.

Can you please point me to the bug and provide more details like platform, monitor, cable.

The bug is at: http://pad.lv/1543683 . All the hardware details should be in the bug report. The cable is a single link dvi-d cable. Unfortunately the bug reporter does not have a dual link cable to test. If you need any additional info, we can ask the bug reporter.

Are you referring to the same issue as Oleksandr reported where a single link dvi/hdmi cable didn’t work and dual link worked?

I'm not sure if this is the exact issue or not. I'll review the other thread and compare.

Regards, Sonika

-----Original Message----- From: Joseph Salisbury [mailto:joseph.salisbury@canonical.com] Sent: Thursday, February 25, 2016 3:09 AM To: Jindal, Sonika sonika.jindal@intel.com Cc: Sharma, Shashank shashank.sharma@intel.com; Vivi, Rodrigo rodrigo.vivi@intel.com; Daniel Vetter daniel.vetter@ffwll.ch; Jani Nikula jani.nikula@linux.intel.com; David Airlie airlied@linux.ie; intel-gfx intel-gfx@lists.freedesktop.org; dri-devel dri-devel@lists.freedesktop.org; LKML linux-kernel@vger.kernel.org Subject: [4.4-rc1][Regression] drm/i915: Check live status before reading edid

Hi Sonika,

A kernel bug report was opened against Ubuntu [0]. After a kernel bisect, it was found that reverting the following commit resolved this bug:

commit 237ed86c693d8a8e4db476976aeb30df4deac74b Author: Sonika Jindal sonika.jindal@intel.com Date: Tue Sep 15 09:44:20 2015 +0530

drm/i915: Check live status before reading edid

The regression was introduced as of v4.4-rc1.

I was hoping to get your feedback, since you are the patch author. Do think increasing the number of tries in intel_hdmi_detect() is worth trying? Do you think gathering any additional data will help diagnose this issue, or would it be best to submit a revert request?

Thanks,

Joe

[0] http://pad.lv/lp1543683

On 03/02/2016 04:58 PM, Joseph Salisbury wrote:

On 02/29/2016 04:33 AM, Jani Nikula wrote:

...

On Wed, 24 Feb 2016, Joseph Salisbury joseph.salisbury@canonical.com wrote:

...

Hi Sonika,

A kernel bug report was opened against Ubuntu [0]. After a kernel bisect, it was found that reverting the following commit resolved this bug:

commit 237ed86c693d8a8e4db476976aeb30df4deac74b Author: Sonika Jindal sonika.jindal@intel.com Date: Tue Sep 15 09:44:20 2015 +0530

drm/i915: Check live status before reading edid

The regression was introduced as of v4.4-rc1.

I was hoping to get your feedback, since you are the patch author. Do think increasing the number of tries in intel_hdmi_detect() is worth trying? Do you think gathering any additional data will help diagnose this issue, or would it be best to submit a revert request?

Thanks for the info. I will have all of these commits tested.

...

There are at least the following commits claiming to fix issues in the above commit. Please make sure you have them.

BR, Jani.

commit 8d409cb3e8a24196be7271defafd4638f3e0b514 Author: Ville Syrjälä ville.syrjala@linux.intel.com Date: Wed Feb 10 19:59:05 2016 +0200

drm/i915: Fix hpd live status bits for g4x

commit 3d8acd1f667b45c531401c8f0c2033072e32a05d Author: Gary Wang gary.c.wang@intel.com Date: Wed Dec 23 16:11:35 2015 +0800

drm/i915: increase the tries for HDMI hotplug live status checking

commit 97f9010af05c15e0b7e6b4ef6ff8cb0ebb7e7715 Author: Daniel Vetter daniel.vetter@ffwll.ch Date: Fri Dec 11 19:44:15 2015 +0100

drm/i915: mdelay(10) considered harmful

commit 0f5a9be15797f78c9a34e432f26c796165b6e49a Author: Imre Deak imre.deak@intel.com Date: Fri Nov 27 18:55:29 2015 +0200

drm/i915: take a power domain reference while checking the HDMI live status

Hi Jani,

Applying the following commit did indeed fix the original bug[0]:

commit 8d409cb3e8a24196be7271defafd4638f3e0b514 Author: Ville Syrjälä ville.syrjala@linux.intel.com Date: Wed Feb 10 19:59:05 2016 +0200

drm/i915: Fix hpd live status bits for g4x

However, it also introduced a new bug, which is covered in that bug report. The new bug is that after locking/unlocking the screen, all the windows get shuffled around in a manner that is consistent with X deciding that it's single-headed again, and then back to double headed. This only happens when I build a kernel with both commit 237ed86c AND commit 8d409cb3e. If I revert 237ed86c and keep only 8d409cb3e both the original bug and the new bug go away. Do you think commit 237ed86c is still even needed now that 8d409cb3e has landed? Maybe the new bug is due to the interaction between 237ed86c and 8d409cb3e.

Thanks,

Joe

[0] http://pad.lv/1543683