Bug 107489

Could you try to reproduce the error using drm-tip (https://cgit.freedesktop.org/drm-tip) and kernel parameters drm.debug=0x1e log_buf_len=4M, and if the problem persists attach the full dmesg from boot. Thanks!

Matt, any luck testing latest drm-tip?

To be honest, I'm loathe to test drm-tip without some evidence that it might actually fix things. I've had this problem with 8 major kernel versions dating back to 2016.

Imre, Manasi, any help here?

(In reply to Matt Turner from comment #3)
> To be honest, I'm loathe to test drm-tip without some evidence that it might
> actually fix things. I've had this problem with 8 major kernel versions
> dating back to 2016.

Matt, could you still provide the full drm.debug=0x1e dmesg log with your current kernel up to the dpms off?

(In reply to Imre Deak from comment #5)
> (In reply to Matt Turner from comment #3)
> > To be honest, I'm loathe to test drm-tip without some evidence that it might
> > actually fix things. I've had this problem with 8 major kernel versions
> > dating back to 2016.
> 
> Matt, could you still provide the full drm.debug=0x1e dmesg log with your
> current kernel up to the dpms off?

I mean dpms off/on.

Created attachment 141086 [details]
drm-debug.log.gz

The attached log was captured with drm.debug=0x1e log_buf_len=4M

Snippet of relevant part (I think):

Aug 14 13:44:32 p50 kernel: [drm:edp_panel_on] Wait for panel power on
Aug 14 13:44:32 p50 kernel: [drm:wait_panel_status] mask b000000f value 80000008 status 0000000a control 00000003
Aug 14 13:44:32 p50 kernel: [drm:gen8_de_irq_handler] hotplug event received, stat 0x01000000, dig 0x12101010, pins 0x00000010
Aug 14 13:44:32 p50 kernel: [drm:intel_hpd_irq_handler] digital hpd port A - long
Aug 14 13:44:32 p50 kernel: [drm:intel_hpd_irq_handler] Received HPD interrupt on PIN 4 - cnt: 0
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_hpd_pulse] ignoring long hpd on eDP port A
Aug 14 13:44:32 p50 kernel: [drm:wait_panel_status] Wait complete
Aug 14 13:44:32 p50 kernel: [drm:intel_power_well_enable] enabling DDI A/E IO power well
Aug 14 13:44:32 p50 kernel: [drm:edp_panel_vdd_on] Turning eDP port A VDD on
Aug 14 13:44:32 p50 kernel: [drm:edp_panel_vdd_on] PP_STATUS: 0x80000008 PP_CONTROL: 0x0000000b
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 00000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 0
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 0
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_program_link_training_pattern] Using DP training pattern TPS1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_start_link_train] clock recovery OK
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_start_link_train] 5.4 Gbps link rate without sink TPS3 support
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_program_link_training_pattern] Using DP training pattern TPS2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 08000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 08000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 08000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 08000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using signal levels 08000000
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using vswing level 2
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_set_signal_levels] Using pre-emphasis level 1
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_dump_link_status] ln0_1:0x11 ln2_3:0x11 align:0x0 sink:0x0 adj_req0_1:0x66 adj_req2_3:0x66
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_start_link_train] Channel equalization failed 5 times
Aug 14 13:44:32 p50 kernel: [drm:intel_dp_start_link_train] *ERROR* [CONNECTOR:71:eDP-1] Link Training failed at link rate = 540000, lane count = 4

Created attachment 141099 [details]
drm-debug.log

debug with plain text

I'm currently testing Manasi's https://patchwork.freedesktop.org/patch/223573/ on top of 4.17.5.

With that patch, the results have been markedly better. After a few days of use, I just got my first black screen on DPMS on. I don't see any messages about link training failing in journalctl. Not sure I can spot any errors in the log.

Created attachment 141227 [details]
drm-debug.log with Manasi's patch

Actually, found it, I was wrong. I see the same Link Training failed message. The attached log contains both the failure and the 'Link Training Passed' message after I suspended the laptop.

Created attachment 141229 [details] [review]
version 2 of test patch

In this case the patch doesnt have any effect and kernel fails to send a uevent to userspace asking to retrain. So uploaded v2 of the patch that unconditionally sends uevent as per Chris Wilson's suggestion.
Userspace will redo modeset a number of times until it decides to give up.
Please try v2 uploaded.

Manasi

Thank you so much. v2 seems to have solved the problem! I've been using it for a week on top of 4.17.5 and have not seen the issue once.

Please have a 

Tested-by: Matt Turner <mattst88@gmail.com>

Thats great! I will submit the patch v2 to the M-L and add your tested by tag to it

Manasi

Presumed fixed by

commit 1e712535c51ab025ebc776d4405683d81521996d
Author: Manasi Navare <manasi.d.navare@intel.com>
Date:   Tue Oct 9 14:28:04 2018 -0700

    drm/i915/dp: Link train Fallback on eDP only if fallback link BW can fit panel's native mode

thanks for the report and testing.

Hi Intel team,

I have a similar bug created at https://bugzilla.kernel.org/show_bug.cgi?id=201547
, but I'm not sure if it has the same root cause as this one here.

I attached dmesg in bug #201547 (https://bugzilla.kernel.org/attachment.cgi?id=279233), with kernel parameters drm.debug=0x1e log_buf_len=4M.

Can you help to confirm?

Thanks a lot!

From the linked kernel log, I'm not seeing any of the same "[drm:intel_dp_start_link_train] *ERROR* [CONNECTOR:71:eDP-1] Link Training failed at link rate = 540000, lane count = 4" type of messages.

Please try with drm-tip, and see if your problem persists. If it does, please open a new FDO bug with your dmesg output from drm-tip with drm.debug=0xe