FS#45733 - [linux] external mini displayport-vga monitor not detected [drm:drm_dp_dpcd_access] too many retries

Attached to Project: Arch Linux
Opened by Chris (kitteboss) - Tuesday, 21 July 2015, 16:55 GMT
Last edited by Allan McRae (Allan) - Saturday, 30 July 2016, 12:53 GMT
Task Type Bug Report
Category Kernel
Status Closed
Assigned To Tobias Powalowski (tpowa)
Architecture x86_64
Severity Medium
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 2
Private No

Details

Description:

Since linux kernel 4.1.x my external vga monitor, connected with a mini displayport to vga adapter is not detected anymore.
xrandr says DP1 disconnected, even if connected and xrandr --output DP1 has no effect.
Downgrading to linux 4.0.7 solves the issue, mini dispalyport to hdmi or dvi adapters are not affected.
Hardware is a macbookpro8,1 with intel sandybridge

Additional info:
* package version(s)
linux 4.1.x
xf86-video-intel 1:2.99.917+381+g5772556-1
xorg-server 1.17.2-4

* config and/or log files etc.
dmesg with drm.debug=14 as kernel parameter gives the following error

[drm:drm_helper_probe_single_connector_modes_merge_bits] [CONNECTOR:40:DP-1]
[drm:intel_dp_detect] [CONNECTOR:40:DP-1]
[drm:drm_dp_dpcd_access] too many retries, giving up
[drm:drm_dp_dpcd_access] too many retries, giving up
[drm:drm_dp_dpcd_access] too many retries, giving up
[drm:drm_dp_dpcd_access] too many retries, giving up

https://bbs.archlinux.org/viewtopic.php?id=199540

Steps to reproduce:
Update to linux 4.1.x and try to connect the vga monitor over the mini displayport
This task depends upon

Closed by  Allan McRae (Allan)
Saturday, 30 July 2016, 12:53 GMT
Reason for closing:  Fixed
Comment by Allan McRae (Allan) - Wednesday, 22 July 2015, 07:49 GMT
This appears to be the cause:

1d002fa720738bcd0bddb9178e9ea0773288e1dd is the first bad commit
commit 1d002fa720738bcd0bddb9178e9ea0773288e1dd
Author: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Date: Tue Feb 10 18:38:08 2015 +0000

drm/dp: Use large transactions for I2C over AUX

Comment by Florian H. (GuyIncognito) - Wednesday, 22 July 2015, 09:13 GMT
Reverting the patch worked for me. I am using an Apple DP-VGA Dongle.
Comment by Vincent Voyer (vvo) - Tuesday, 28 July 2015, 08:25 GMT
It seems since I updated to:

[2015-07-25 10:30] [ALPM] upgraded linux (4.0.7-2 -> 4.1.2-2)
[2015-07-25 10:31] [ALPM] upgraded xf86-video-intel (1:2.99.917+364+gb24e758-1 -> 1:2.99.917+381+g5772556-1)
[2015-07-25 10:31] [ALPM] upgraded xorg-server-common (1.17.2-3 -> 1.17.2-4)
[2015-07-25 10:31] [ALPM] upgraded xorg-server (1.17.2-3 -> 1.17.2-4)
[2015-07-25 10:31] [ALPM] upgraded xorg-server-xvfb (1.17.2-3 -> 1.17.2-4)

My Thinkpad T550 mini display port is no more working.

Do I need to downgrade kernel and or xf86 etc.. ?
Comment by Florian H. (GuyIncognito) - Tuesday, 28 July 2015, 09:09 GMT
Just downgrading the kernel should do the trick.
Comment by Vincent Voyer (vvo) - Tuesday, 28 July 2015, 09:21 GMT
GuyIncognito I tried to look at the docs of archlinux to do so but could not find
the relevant information. It seems not so easy to do, I do not want to again
break my machine by downgrading.

I switched to VGA monitor for now.

If you have an easy way, can link to the relevant wiki page, it would be great.

Thanks for your bug report thought, good community work!

Don't you think we should report this to the kernel bug tracker?
Comment by Florian H. (GuyIncognito) - Tuesday, 28 July 2015, 09:30 GMT
Just to be clear if your problem is the same as in the bug report, are you using a DisplayPort-to-VGA adapter (and if so, which one?)

Here is the related wiki entry: https://wiki.archlinux.org/index.php/Downgrading_packages#Downgrading_the_kernel

You don't need to boot from a live CD, just go to /var/cache/pacman/pkg and install the appropriate kernel Version.
Comment by Vincent Voyer (vvo) - Tuesday, 28 July 2015, 09:34 GMT
I have a mini display port on my thinkpad T550.

It's connected to a HDMI screen through a mini display port => HDMI cable.

It stopped working right after upgrading (yesterday):
[2015-07-25 10:30] [ALPM] upgraded linux (4.0.7-2 -> 4.1.2-2)
[2015-07-25 10:31] [ALPM] upgraded xf86-video-intel (1:2.99.917+364+gb24e758-1 -> 1:2.99.917+381+g5772556-1)
[2015-07-25 10:31] [ALPM] upgraded xorg-server-common (1.17.2-3 -> 1.17.2-4)
[2015-07-25 10:31] [ALPM] upgraded xorg-server (1.17.2-3 -> 1.17.2-4)
[2015-07-25 10:31] [ALPM] upgraded xorg-server-xvfb (1.17.2-3 -> 1.17.2-4)

I do think that it's exactly the same patch that is causing this, otherwise it would be a hell of a coincidence.

Intel chipset is i915:
00:02.0 VGA compatible controller: Intel Corporation Broadwell-U Integrated Graphics (rev 09)
Subsystem: Lenovo Device 2223
Kernel driver in use: i915
Kernel modules: i915

What do you think?
Comment by Florian H. (GuyIncognito) - Tuesday, 28 July 2015, 09:39 GMT
Well you could try out downgrading. Until now this problem seemed to be miniDP-VGA related, the original poster of this bug said miniDP-HDMI is working for him, so I guess your problem is a different one, although I am not sure.
Comment by Vincent Voyer (vvo) - Tuesday, 28 July 2015, 09:41 GMT
It would be an amazing coincidence that both of them are not linked. Depending on the hardware maybe.

Do we need to open a bug report on feredesktop or kernel.org?
Comment by Florian H. (GuyIncognito) - Tuesday, 28 July 2015, 09:57 GMT
Oh I already opened a bug report at freedekstop but haven't received an answer yet.

https://bugs.freedesktop.org/show_bug.cgi?id=91451
Comment by Allan McRae (Allan) - Saturday, 30 July 2016, 12:53 GMT
This bug is old and was fixed for me. Also appears the upstream bug was resolved as fixed. Closing.

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