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

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Message-ID: <56CF4AE8.6020706@canonical.com>
Date:	Thu, 25 Feb 2016 13:41:44 -0500
From:	Joseph Salisbury <joseph.salisbury@...onical.com>
To:	"Jindal, Sonika" <sonika.jindal@...el.com>
Cc:	"Sharma, Shashank" <shashank.sharma@...el.com>,
	"Vivi, Rodrigo" <rodrigo.vivi@...el.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	intel-gfx <intel-gfx@...ts.freedesktop.org>,
	dri-devel <dri-devel@...ts.freedesktop.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"oleksandr@...alenko.name" <oleksandr@...alenko.name>
Subject: Re: [4.4-rc1][Regression] drm/i915: Check live status before reading
 edid

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@...onical.com] 
> Sent: Thursday, February 25, 2016 3:09 AM
> To: Jindal, Sonika <sonika.jindal@...el.com>
> Cc: Sharma, Shashank <shashank.sharma@...el.com>; Vivi, Rodrigo <rodrigo.vivi@...el.com>; Daniel Vetter <daniel.vetter@...ll.ch>; Jani Nikula <jani.nikula@...ux.intel.com>; David Airlie <airlied@...ux.ie>; intel-gfx <intel-gfx@...ts.freedesktop.org>; dri-devel <dri-devel@...ts.freedesktop.org>; LKML <linux-kernel@...r.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@...el.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
>