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

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Date:	Fri, 26 Feb 2016 11:38:54 +0530
From:	"Jindal, Sonika" <sonika.jindal@...el.com>
To:	Joseph Salisbury <joseph.salisbury@...onical.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>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>
Subject: Re: [4.4-rc1][Regression] drm/i915: Check live status before reading
 edid



On 2/26/2016 12:11 AM, Joseph Salisbury wrote:
> 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.
If this is with single link cable, the issue could be the same.
As Ville suggested for the other issue to use video=HDMI-A-1:e as 
command line argument, can you please give it a try?
The logs shared in the bug doesn't have drm logs enabled, so couldnt get 
much out of it.
Which platform is this?

Alternatively you can add something like following in intel_hdmi_detect 
to make it ignore the live status checks.

@@ -1419,7 +1419,7 @@ intel_hdmi_detect(struct drm_connector *connector, 
bool force)

         intel_hdmi_unset_edid(connector);
-
+       live_status = live_status | force;
         if (intel_hdmi_set_edid(connector, live_status)) {
                 struct intel_hdmi *intel_hdmi = 
intel_attached_hdmi(connector);


Regards,
Sonika
>> 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
>>
>