Re: [4.4-rc1][Regression] drm/i915: Check live status before reading edid

From: Joseph Salisbury <joseph.salisbury@canonical.com>
To: "Jindal, Sonika" <sonika.jindal@intel.com>
Cc: David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	intel-gfx <intel-gfx@lists.freedesktop.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"oleksandr@natalenko.name" <oleksandr@natalenko.name>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	"Vivi, Rodrigo" <rodrigo.vivi@intel.com>
Subject: Re: [4.4-rc1][Regression] drm/i915: Check live status before reading edid
Date: Thu, 25 Feb 2016 13:41:44 -0500	[thread overview]
Message-ID: <56CF4AE8.6020706@canonical.com> (raw)
In-Reply-To: <000C66961D35964B9714611E548C10AD0C3FF620@BGSMSX104.gar.corp.intel.com>

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
>


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