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ADV7482: HDCP issue when input source switching.

Category: Hardware
Product Number: ADV7482

Hi,

I describe detail of problem below.

■Background
Our customer uses ADV7482 for their project.
He's faced with a problem now.
He can see the video image correctly both of HDMI and CVBS input source.
But a problem occurs when the input is changed.

■The problem the customer is faced with.
At first, the customer can see HDMI video image from the DVD player using HDCP on the display.
The HDMI input is selected (csi4_in_sel[1:0] = 00) to MIPI Tx A port.
At this time,
hdmi_encrpt_a_raw (IO Map, Address 0x71[5] (Read Only)) = 1
hdmi_content_encrypted (HDMI RX Map, Address 0x05[6] (Read Only)) = 1
These registers are both "1" because video data with HDCP input from the DVD player.

Next, the CVBS input is selected (csi4_in_sel[1:0] = 1x) to MIPI Tx A port.
The customer can see the CVBS Video. It's no problem.
The register settings for input select are as follows:
Device Address Map Register Address Value
SDP Map 0x00 0x0E
TxA Map 0x31 0x82
0x1E 0x00
0x00 0x81
0xDA 0x00
0xC1 0x3B
IO Map 0x10 0x88
TxA Map 0x00 0x81
0x00 0xA1
0xD2 0x40
0xC4 0x0A
0x71 0x33
0x72 0x11
0xF0 0x00
0x31 0x82
0x1E 0x40
0xDA 0x01
Wait 100[ms]
TxA Map 0x00 0x21
Wait 1[ms]
TxA Map 0xC1 0x2B
Wait 1[ms]
TxA Map 0x31 0x80
IO Map 0x04 0x02

At this time, Case 1: When HDMI input is selected again within 2 seconds since CVBS input is selected, the HDMI input can be seen.
At this time,
hdmi_encrpt_a_raw (IO Map, Address 0x71[5] (Read Only)) = 1
hdmi_content_encrypted (HDMI RX Map, Address 0x05[6] (Read Only)) = 1
These registers are kept "1", and he can see the HDMI input video correctly.

Case 2: When HDMI input is selected again after about 3 seconds or more since CVBS input is selected, the HDMI input can not be seen.
At this time,
hdmi_encrpt_a_raw (IO Map, Address 0x71[5] (Read Only)) = 0
hdmi_content_encrypted (HDMI RX Map, Address 0x05[6] (Read Only)) = 0
These registers are changed to "0", and he can not see the HDMI input video.
After that, HotPlug (HPA) has to be asserted (toggled, High => Low => High) in order to restore so that the HDMI input can be seen.

but customer doesn't want to use HotPlug assertion in this case.

The register settings that the HDMI input is selected are as follows:
Device Address Map Register Address Value
TxA Map 0x31 0x82
0x1E 0x00
0x00 0x82
0xDA 0x00
0xC1 0x3B
IO Map 0x10 0x80
TxA Map 0x00 0x82
0x00 0xA2
0xDB 0x10
0xD6 0x07
0x71 0x33
0x72 0x33
0xF0 0x00
0x31 0x82
0x1E 0x40
0xDA 0x01
Wait 100[ms]
TxA Map 0x00 0x22
Wait 1[ms]
TxA Map 0xC1 0x2B
Wait 1[ms]
TxA Map 0x31 0x80
IO Map 0x04 0x00

We think that this problem seems that HDCP 3rd authentication is related when the input is selected.
And the cusotmer tried "64 40 83 ; Enable HDCP 1.1". (HDCP 1.1 feature enables). But, this problem (case 2) could not be resolved.

■Qusetions:
Q1: What should the customer do to resolve this problem?
Is there any method for keeps "hdmi_encrpt_a_raw = 1" and "hdmi_content_encrypted = 1" when the input is changed from HDMI to CVBS and HDMI is selected again?

Q2: Is this phenomenon (case 2) a specification for the ADV7482?
Is it possible to solve this problem?

Thank you for your support!

  • Hi,

      Please crosscheck your 'HDMI input register settings' with reference configuration at ":01-11 HDMI to MIPI TxA CSI 2-Lane - YUV422 8-Bit, Up to 600Mbps"

      Also some of the recommended writes are not matched according to the reference script. Please refer below writes.

      If those writes are not included, I would not expect the part to work reliably (unless those values are default anyway).Those registers are generally internal settings that let us handle process variation which is why they are determined during characterization.

     94 72 11;  ADI Required Write // 0x72 0x33
     94 4 0A;  ADI Required Write are not provided in case 2 script

    Thanks,

    Poornima

  • Hi Poornima-san

    Thank you for your reply.

    Our customer is trying to evaluate with your recommended register setting.

    if they completed it, i'll inform you.

    Then, I have a question for you.

    I referred recommended script on below URL.

    http://www.analog.com/media/en/engineering-tools/design-tools/ADV7481ES3C-VER.3.6c.txt

    But I could not find your recommended setting. "94 4 0A"

    And there is no description on Data sheet, UG-747, hardware design guide etc... regarding TXA Map 0x04.

    Could you disclose explanation of this register (TX A Map 0x04)?

    Thanks,

    Nishimoto.

  • Hi Hirotaka San,

      Please find the below comments,

      I could not find your recommended setting. "94 4 0A" .

         Sorry that was a typo error, the register address was C4 not 04 ( 94 C4 0A).

     Could you disclose explanation of this register (TX A Map 0x04) ?

           Those writes are generally determined at characterization and We don't disclose the details.
           These writes are for internal engineering reasons. We generally do not share these with customers.

    Note: "ADI Recommended/Required write" register sequence should be followed as like as script file.We regard these writes as non user adjustments and hence their function is not documented. Please refer here ADI Recommended Setting

    Thanks,

    Poornima

  • Hi Poornima-san,

    Thank you for your reply.

    Customer had tried input source switching with 94 72 11 and 94 C4 0A but not improved this issue. I think above recommended registers are just for MIPI TXA, this issue occurred in HDCP block.

    Could you please answer the first questions again?

    Q1: What should the customer do to resolve this problem?

    Q2: Is this phenomenon (case 2) a specification for the ADV7482?

    Thanks,

    Nishimoto.

  • Hi Hirotaka San,

           Please let us know, How long are you waiting during the Case2 Scenario (i.e How fast are you doing the HPD)?

           Generally the HDCP re-authentication when switching from one source to another (topology changes).  long delay Of these the HDCP is usually the slowest one to happen.

    Also please note BCAPS register must be initialized appropriately if these features(HDCP 1.1_features, fast reauthentication, and fast_i2c speed ) are to be supported by the application that integrating the ADV748x.

    Ensure with BCAPS[4] bit as "400KHz transfers are not permitted to any device unless all devices on the I2C bus are capable of 400KHz transfer"

    Please refer below image about BCAPS register bit details,

    Thanks,

    Poornima

  • Hi Poornima-san,

    >Please let us know, How long are you waiting during the Case2 Scenario (i.e How fast are you doing the HPD)?

    As I mentioned my first message, customer doesn't do HPD when switch back to HDCP source from CVBS because they have to minimize mute period when input source switching.

    In such case, once choose HDCP source, then switch to CVBS source and switch back to HDCP source, ADV7482 requires HDP again?

    >Generally the HDCP re-authentication when switching from one source to another (topology changes).  long delay Of these the HDCP is usually the slowest one to happen.

    Sorry, I could not understand. 

    Let me clear ADV7482 design limitation during switching from HDCP source to CVBS source and switch back to HDMI/HDCP source, ADV7482 requires HDMI re-authentication and re-HPD from first part of authentication?

    Thanks,

    Nishimoto.

  • Hi Hirotaka San,

    In such case, once choose HDCP source, then switch to CVBS source and switch back to HDCP source, ADV7482 requires HDP again ?

        Actually HPD is not required when switching the source between CVBS and HDCP but here we don't observe such issues in our eval board even when we increase the switching delay.

    Thanks,

    Poornima   

  • Hi Poornima-san,

    Thank you for your comment.
    How about below my question?

    >Let me clear ADV7482 design limitation during switching from HDCP source to CVBS source and switch back to HDMI/HDCP source, ADV7482 requires HDMI re-authentication and re-HPD from first part of authentication.

     

  • Hi Hirotaka San,

           As stated earlier, Re-HPD/Reauthentication is not required when switching between HDCP and CVBS Source.

    Thanks,

    Poornima

  • Hi Hirotaka San,

           Please find our below connection setup in our eval board while switching between HDMI and CVBS source,

              "QD 804B(HDCP / CVBS)" --> EVAL ADV7482 --> VA1838 Analyzer.

    Also Kindly note, In our software we are "Reauthenticating the HDCP" While switching between HDMI and CVBS Source and this we have confirmed by from our debug log (Debug Print "HDCP RESET" ).

    Thanks,

    Poornima