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SN65DSI83-Q1: NO LVDS output Reading 0xE5 and it shows 0x3d

santhana kumar s
Expert 1535 points
Part Number: SN65DSI83-Q1
Other Parts Discussed in Thread: DSI-TUNER

Tool/software:

Hi, 

We are working in the SN65DSI83-Q1 and integrated with the LTK101FTNCT54 display in the SC668s som board the issue is the DISPLAY not working  and it doesn;t show the Test pattern also.

Below the schematics added



Logs :
trinket:/ # i2cdump -f -y 2 0x2c 
     0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: 35 38 49 53 44 20 20 20 01 00 03 10 00 01 00 00 58ISD ?.??.?..
10: 26 00 1e 00 00 00 00 00 78 00 03 00 00 00 00 00 &.?.....x.?.....
20: 00 04 00 00 00 00 00 00 21 00 00 00 14 00 00 00 .?......!...?...
30: 03 00 00 00 a0 00 17 00 a0 00 0c 00 10 00 00 00 ?...?.?.?.?.?...
40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
e0: 00 00 00 00 00 3d 00 00 00 00 00 00 00 00 00 00 .....=..........
f0: 00 00 00 00 40 00 00 80 00 00 00 00 00 00 00 00 ....@..?........
trinket:/ # 

Debugged the issue in the below method:
1. Checked the 0xe5 registers it showing 0x3d which means there is error.
2. After enabled the CONVERT_DEBUG in driver file 
3. Writes 0xFF in register 0xe5 
4. After its read 0x01 still the error shows.
Note:
sometimes the 0x0a shows if the Android screen wakes it shows the 0x83 and the android screen goes sleep then t shows 0x03

Can you please help us to resolve the issue
Regards,SanthanaKumarS
  • 0
    TI__Genius 9190 points

    Hi, 

    Can you provide the panel specifications? Did you follow Section 8.2.2.Detailed Procedure to program the registers? 

    When the Android screen goes to sleep, is the video stopping?

    If it is, then you would need to restart the sequence for the device to restart video. 

    santhana kumar s said:
    4. After its read 0x01 still the error shows.

    It seems when it goes to sleep, this causes the PLL to not be enabled in Register 0xa, which matches what you see in Register 0xe5 - PLL_UNLOCK error. Can you try clearing Register 0xe5 multiple times and rereading to see if there is still a PLL_UNLOCK issue when the device is not asleep? 

    Were you able to follow this initialization sequence based on the datasheet? 

    BR,

    Esther

  • 0 in reply to Esther Chang
    Expert 1535 points

    We have followed the program sequence correctly because we are working in the SC668s SOM board and the Quectel vendor provided the working source code to us.

    Below the panel specifications:

                                    qcom,mdss-dsi-panel-width = <1024>;
                                    qcom,mdss-dsi-panel-height = <600>;
                                    qcom,mdss-dsi-h-front-porch = <160>;
                                    qcom,mdss-dsi-h-back-porch = <160>;
                                    qcom,mdss-dsi-h-pulse-width = <20>;
                                    qcom,mdss-dsi-h-sync-skew = <0>;
                                    qcom,mdss-dsi-v-back-porch = <23>;
                                    qcom,mdss-dsi-v-front-porch = <12>;
                                    qcom,mdss-dsi-v-pulse-width = <3>;

    Test pattern also configured and the panel doesn't response and what we observed this the below one 

    0xE5 getting 0x01 and after continuous writing of 0xFF.

    There is no android screen and test pattern displayed and observed the below 
    Android scrren on -> Reads 0xa register and it shows 0x83
    Android screen off -> Reads 0xa register and it shows 0x03

    We are shared the i2c dump nd you can see the configuration in SN65dsi83-Q1
  • 0 in reply to santhana kumar s
    TI__Genius 9190 points

    Hi,

    Are you using the DSI-TUNER tool - https://e2e.ti.com/support/interface-group/interface/f/interface-forum/825302/sn65dsi83-dsi-tuner-tool-needed to bring up PATGEN?

    Esther Chang said:

    When the Android screen goes to sleep, is the video stopping?

    If it is, then you would need to restart the sequence for the device to restart video. 

    Can you please let me know about these points?

    Esther