<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - DP monitor does not get activated when snd_hda_intel is loaded" href="https://bugs.freedesktop.org/show_bug.cgi?id=75710#c5">Comment # 5</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - DP monitor does not get activated when snd_hda_intel is loaded" href="https://bugs.freedesktop.org/show_bug.cgi?id=75710">bug 75710</a> from <a class="email" href="mailto:consume.noise@gmail.com" title="Daniel Martin <consume.noise@gmail.com>"> Daniel Martin</a> <pre>So, this took me a while (failed at bisecting etc.). One reason was the assumption that v3.6 is fine, which isn't true. Additionally, I made observations that help me to see from the dmesg if it's working or if the monitor will switch into suspend mode (more on this at the end). I bisected it down to commit (v3.6-rc1): 2514bc5 drm/i915: prefer wide & slow to fast & narrow in DP configs Reverting it on top of v3.6 fixes the problem. The used lanes drop and the clock raises from: [drm:intel_dp_compute_config], DP link bw 06 lane count 4 clock 162000 bpp 24 to: [drm:intel_dp_compute_config], DP link bw 0a lane count 2 clock 270000 bpp 24 But, that's the complete opposite why this commit/fix has been added: <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - [SNB DP regression] no signal via DisplayPort since Linux 3.2" href="show_bug.cgi?id=45801">https://bugs.freedesktop.org/show_bug.cgi?id=45801</a> So, reverting it may cause trouble at other maschines. Then, I have switched to v3.14-rc5 for further testing: 1. Reverting 2514bc5 on top of v3.14-rc5 fixes the problem too. The next observatins have been done _without_ the revert - plain v3.14-rc5. 2. In my initial tests `xrandr --output DP2 --set audio off` didn't changed the result. Now, it works reliable. The problem is gone. 3. [drm:ilk_display_irq_handler], Pipe B FIFO underrun If I see this message after a `xrandr --output DP2 --preferred`, while the audio property is at its default (auto), then I know that the monitor will switch on and everything is fine. If I don't see it, the monitor will switch into standby. I hope that at least the last observation is helpful.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are on the CC list for the bug.</li> </ul> </body> </html>