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<p class="MsoPlainText">Please find My replay.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Thanks<o:p></o:p></p>
<p class="MsoPlainText">Sridhar<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">-----Original Message-----<br>
From: Takashi Iwai [mailto:tiwai@suse.de] <br>
Sent: Thursday, January 26, 2017 7:50 PM<br>
To: Ville Syrjälä <ville.syrjala@linux.intel.com><br>
Cc: intel-gfx <intel-gfx@lists.freedesktop.org>; Michal Marek <mmarek@suse.cz>; Chen, Angus <angus.chen@intel.com>; Jeffrey Cheung <jcheung@suse.com>; Hsu, Ray <ray.hsu@intel.com>; Venkatanara, Sridhara <Sridhara_Venkatanara@DELL.com><br>
Subject: Re: [Intel-gfx] Broken DPMS with DisplayPort on CHV (also BYT?)</p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">On Thu, 26 Jan 2017 14:58:55 +0100,<o:p></o:p></p>
<p class="MsoPlainText">Ville Syrjälä wrote:<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> On Wed, Jan 25, 2017 at 01:56:35PM +0100, Takashi Iwai wrote:<o:p></o:p></p>
<p class="MsoPlainText">> > Hi,<o:p></o:p></p>
<p class="MsoPlainText">> > <o:p></o:p></p>
<p class="MsoPlainText">> > we've got a bug report about the blank monitor on Cherry Trail
<o:p></o:p></p>
<p class="MsoPlainText">> > machines. And, Intel team (Cc'ed) spotted out that this seems
<o:p></o:p></p>
<p class="MsoPlainText">> > triggered by DPMS transition. A patch like below actually fixes the
<o:p></o:p></p>
<p class="MsoPlainText">> > problem.<o:p></o:p></p>
<p class="MsoPlainText">> > <o:p></o:p></p>
<p class="MsoPlainText">> > Of course it doesn't look like a right "fix". Do you guys have any
<o:p></o:p></p>
<p class="MsoPlainText">> > hint for further debugging?<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> Is it some kind of new fangled MST capable monitor? I've noticed that
<o:p></o:p></p>
<p class="MsoPlainText">> those tend to be super easy to mess up.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">The monitors are in Dell team. Sridhara, could you give details about the problematic monitors?<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><span style="font-size:12.0pt">[Sridhar] Monitor types E2316H, E2216H<o:p></o:p></span></p>
<p class="MsoPlainText"><a href="http://www.dell.com/ed/business/p/dell-e2316h-monitor/pd">http://www.dell.com/ed/business/p/dell-e2316h-monitor/pd</a> <o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">> > Some more (not alt-) facts:<o:p></o:p></p>
<p class="MsoPlainText">> > <o:p></o:p></p>
<p class="MsoPlainText">> > - The machine we've tested is a Cherry Trail based box with two<o:p></o:p></p>
<p class="MsoPlainText">> > DisplayPorts. Intel team mentioned that there are other machines<o:p></o:p></p>
<p class="MsoPlainText">> > suffering from the same problem.<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> Is it really somehow tied to the machine? I would imagine it should
<o:p></o:p></p>
<p class="MsoPlainText">> behave exactly the same way no matter what machine you have.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">A good question. Again the question is delegated to Sridhara :)<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><span style="font-size:12.0pt">[Sridhar] It is tied to the Cherry Trail based box. Not observed with Bay Trail machines.<o:p></o:p></span></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">> > - With some monitors, the screen remains blank during boot and on X.<o:p></o:p></p>
<p class="MsoPlainText">> > This can be cured after "xset dpms force off" and resume, or<o:p></o:p></p>
<p class="MsoPlainText">> > reconfiguring via xrandr.<o:p></o:p></p>
<p class="MsoPlainText">> > <o:p></o:p></p>
<p class="MsoPlainText">> > - The issue seems specific to DP connections. When two (identical)<o:p></o:p></p>
<p class="MsoPlainText">> > monitors are connected, only one monitor goes blank.<o:p></o:p></p>
<p class="MsoPlainText">> <o:p></o:p></p>
<p class="MsoPlainText">> Hmm. Have you tried 9f2bdb006a7e ("drm/i915: Prevent PPS stealing from
<o:p></o:p></p>
<p class="MsoPlainText">> a normal DP port on VLV/CHV") ?<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">No, it's not tested. I'll prepare a test kernel with it.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Thanks!<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Takashi<o:p></o:p></p>
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