Dp aux error

Hi, the dp port had the aux error as follow sometimes, why this?
[ 5583.427262] tegradc tegradc.1: dp: aux read retry (0x10000100) – 2
[ 5583.428763] tegradc tegradc.1: dp: aux read retry (0x10000100) – 1
[ 5583.430268] tegradc tegradc.1: dp: aux read retry (0x10000100) – 0
[ 5583.431779] tegradc tegradc.1: dp: aux read got error (0x10000100)
[ 5583.431790] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0x202, Status 0x10000100
[ 5583.432474] tegradc tegradc.1: dp: aux read retry (0x10000100) – 2
[ 5583.433979] tegradc tegradc.1: dp: aux read retry (0x10000100) – 1
[ 5583.435497] tegradc tegradc.1: dp: aux read retry (0x10000100) – 0
[ 5583.437020] tegradc tegradc.1: dp: aux read got error (0x10000100)
[ 5583.437032] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0x203, Status 0x10000100
[ 5583.437037] dp lt: CR lost
[ 5583.437046] dp lt: switching from state 3 (channel equalization) to state 6 (reduce link rate)
[ 5583.437056] dp lt: state 6 (reduce link rate), pending_lt_evt 0
[ 5583.437065] dp lt: link rate already lowest
[ 5583.437773] tegradc tegradc.1: dp: aux write retry (0x10000100) – 2
[ 5583.439304] tegradc tegradc.1: dp: aux write retry (0x10000100) – 1
[ 5583.440828] tegradc tegradc.1: dp: aux write retry (0x10000100) – 0
[ 5583.442353] tegradc tegradc.1: dp: aux write got error (0x10000100)
[ 5583.442365] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x102, Status 0x10000100
[ 5583.443379] tegradc tegradc.1: dp: aux write retry (0x10000100) – 2
[ 5583.444903] tegradc tegradc.1: dp: aux write retry (0x10000100) – 1
[ 5583.446423] tegradc tegradc.1: dp: aux write retry (0x10000100) – 0
[ 5583.447951] tegradc tegradc.1: dp: aux write got error (0x10000100)
[ 5583.447962] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x100, Status 0x10000100
[ 5583.448894] tegradc tegradc.1: dp: aux read retry (0x10000100) – 2
[ 5583.450418] tegradc tegradc.1: dp: aux read retry (0x10000100) – 1
[ 5583.451966] tegradc tegradc.1: dp: aux read retry (0x10000100) – 0
[ 5583.453517] tegradc tegradc.1: dp: aux read got error (0x10000100)
[ 5583.453529] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0x101, Status 0x10000100
[ 5583.453543] tegradc tegradc.1: DP: no prod_c_hbr prod settings node in device tree

Issue happened at which JetPack version?
On devkit or with custom carrier board?
How to reproduce it?

JetPack4.5, R32.5.1
It happend on our board, it is probabilistic. we don’t know why this?
From which direction can you view the cause?

  1. Check if the same monitor can pass link training on devkit first.

  2. If (1) passes, review the hardware design and device tree configuration on your board. If power is not correctly on, then you would see “Failed to write DPCD data” easily.

Hi , when dp hpd disconnect, what will dp do? we catched the log as follow, is it right?
[148.664664] tegradc tegradc.1: dp: unplug event received
[ 148.744492] hpd: state 3 (Disabled), hpd 1, pending_hpd_evt 1
[ 148.744514] hpd: switching from state 3 (Disabled) to state 0 (Reset)
[ 148.845768] hpd: state 0 (Reset), hpd 1, pending_hpd_evt 0
[ 148.845802] tegradc tegradc.1: blank - powerdown
[ 148.845844] tegradc tegradc.1: dp: HPD is not detected
[ 148.845859] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.845871] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.845885] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.845921] tegradc tegradc.1: dp: HPD is not detected
[ 148.845949] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.845968] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.845991] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.846036] tegradc tegradc.1: dp: HPD is not detected
[ 148.846059] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.846078] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.846102] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.846144] tegradc tegradc.1: dp: HPD is not detected
[ 148.846168] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.846186] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.846202] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.846225] tegradc tegradc.1: dp: HPD is not detected
[ 148.846236] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.846245] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.846256] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.846279] tegradc tegradc.1: dp: HPD is not detected
[ 148.846289] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 148.846298] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 148.846309] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 148.998505] extcon-disp-state extcon:disp-state: cable 44 state 0 already set.
[ 148.998508] Extcon DP: HPD disabled
[ 148.998510] hpd: hpd_switch 0
[ 148.998513] hpd: switching from state 0 (Reset) to state 1 (Check Plug)
[ 148.998525] hpd: state 1 (Check Plug), hpd 1, pending_hpd_evt 0
[ 148.998528] hpd: switching from state 1 (Check Plug) to state 2 (Check EDID)
[ 149.005516] hpd: state 2 (Check EDID), hpd 1, pending_hpd_evt 0
[ 149.005532] tegradc tegradc.1: dp: HPD is not detected
[ 149.010702] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x600, Status 0x0
[ 149.010712] tegradc tegradc.1: dp: HPD is not detected
[ 149.010715] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x600, Status 0x0
[ 149.010723] tegradc tegradc.1: dp: HPD is not detected
[ 149.010725] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x600, Status 0x0
[ 149.010733] tegradc tegradc.1: dp: HPD is not detected
[ 149.010735] tegradc tegradc.1: dp: Failed to write DPCD data. CMD 0x600, Status 0x0
[ 149.010738] tegradc tegradc.1: dp: failed to exit panel power save mode (0xfffffff2)
[ 149.010755] hpd: edid read prepare failed
[ 149.010755] tegradc tegradc.0: blank - powerdown
[ 149.068542] tegradc tegradc.1: blank - powerdown
[ 149.068558] tegradc tegradc.1: dp: HPD is not detected
[ 149.068562] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068564] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068568] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.068577] tegradc tegradc.1: dp: HPD is not detected
[ 149.068579] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068581] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068583] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.068591] tegradc tegradc.1: dp: HPD is not detected
[ 149.068593] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068595] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068597] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.068605] tegradc tegradc.1: dp: HPD is not detected
[ 149.068608] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068610] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068612] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.068620] tegradc tegradc.1: dp: HPD is not detected
[ 149.068622] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068623] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068626] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.068633] tegradc tegradc.1: dp: HPD is not detected
[ 149.068635] tegradc tegradc.1: dp: Failed to read DPCD data. CMD 0xe, Status 0x0
[ 149.068637] tegradc tegradc.1: dp: Failed to read ext DPCD caps
[ 149.068639] tegradc tegradc.1: dp: Invalid link rate (0) or lane count (4)
[ 149.207626] tegradc tegradc.1: dp: plug event received
[ 149.220424] extcon-disp-state extcon:disp-state: cable 44 state 0 already set.
[ 149.220426] Extcon DP: HPD disabled
[ 149.220428] hpd: hpd_switch 0
[ 149.220430] hpd: switching from state 2 (Check EDID) to state 3 (Disabled)
[ 149.220434] hpd: state 3 (Disabled), hpd 1, pending_hpd_evt 1
[ 149.220436] hpd: switching from state 3 (Disabled) to state 0 (Reset)
[ 149.220473] tegradc tegradc.1: blank - powerdown
[ 149.222760] tegradc tegradc.0: blank - powerdown
[ 149.244605] tegradc tegradc.1: blank - powerdown
[ 149.321522] hpd: state 0 (Reset), hpd 1, pending_hpd_evt 0
[ 149.321535] tegradc tegradc.1: blank - powerdown
[ 149.321980] tegradc tegra_dc_set_fb_mode:pclk=297000000,hact=3840,v_act=1080,vmode=0x200000
[ 149.322013] extcon-disp-state extcon:disp-state: cable 44 state 0 already set.
[ 149.322016] Extcon DP: HPD disabled

請問你的意思是你拔掉dp線之後你還是會看到那些error嗎

Are you saying that if you plug out the DP cable and you would still see those error?

yes! The errors don’t mean there’s a problem, right?

我是建議你們還是檢查一下硬體部份有沒有問題…

"Failed to read DPCD data. " 這種錯誤基本上就跟你沒接電所以導致timeout error是類似的情況…
從這種log來看基本上也沒辦法確認到底哪邊有問題.

I would suggest to check your hardware design.
"Failed to read DPCD data. " is similar to “timeout” error that coming out when you have no power.
From such log, basically it is hard to know what goes wrong…

谢谢回复,dp 断开的,后面的错误error应该是正常的,对吧?
dp hpd断开的话, dp 是收到了 unplug event received, 然后下面的error是不是就是正常的,
dp断开是我们主动断开了下

不是…那個error不是正常的

基本上很多問題你可以先比照devkit上面的狀況.

No, that error log is abnormal.
Actually you can compare the log on devkit and you will know the answer.