SN65DSI86: spec check

GARETH OU

Part Number: SN65DSI86

Tool/software:

Customers are using the Android15 platform with the mtk main chip mt8786 and TI's mipi to edp signal adapter chip TI SN65DSI86 chip and are currently experiencing the following problems

1.The SN65DSI86 chip must use REFCLK to light up normally in color mode, and it cannot light up normally using MIPI CLk.

2. When SN65DSI86 is in normal working mode, the EDP output is measured to have a signal, and the signal waveform is consistent with that in color mode (waveform and amplitude), but the screen cannot be lit. What kind of mipi clock and signal input does this conversion chip require? Can it only use the mipi clock in normal mode?

Thank you

4 months ago

0 Ikram Haque 4 months ago

TI__Mastermind 22830 points

Hi Gareth,

1. Have you tested it working with test pattern? With the test pattern it outputs video without DSI input to test the DP interface and display.

Please use the calculator tool from this link to generate the I2C initialization script: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1382976/faq-sn65dsi8x-programming-tools

Are you programming the REFCLK and MIPI clock at the same rate? Please share the rates and timings you are using and also dump the registers 0xF0 - 0xF8 when the issue occurs so that we can verify which errors are causing this.

2. What do you mean by normal mode?

Please share the display timings including pixel clock rates, DSI clock frequency and lane rates.

Also, can you tell us more about your test setup:
- are you using the TI EVM or a custom board with the DSI86 chip on it?
- how are you connecting the DSI interface?
- does this issue occur every time or occasionally? Has the display worked with DSI clock with the current procedure?

Best regards,
Ikram

0 GARETH OU 3 months ago in reply to Ikram Haque

Guru 11375 points

Hi Ikram

Thanks for your support.

We test with the test pattern with the REFCLK instead of MIPI CLK input.

I want to make sure that the test pattern only can work with REFCLK, does it can work with MIPI CLK.

2. The normal mode means not work in test pattern, does it need to work with MIPI CLK or REFCLK

We dump the register form 0XF0 to 0XF8, The 0XF6 BIT 6 is error, how can I solve it

The design as below:

I use MIPI_CLK instead of REFCLK and set the register through i2c as below, the 0xF0~0xF8 have not error

static sn65dsi8x_setting_table sn65dis86_init_release_table[] = {

{0x09,0x00},

{0x0A,0x09},

{0x0D,0x01},

{0x64,0x01},

{0x74,0x00},

{0x75,0x01},

{0x76,0x0A},

{0x77,0x01},

{0x78,0x81},

{0x5A,0x05},

{0x10,0x26},

{0x11,0x00},

{0x12,0x5c},

{0x13,0x5c},

{0x20,0x80},

{0x21,0x07},

{0x22,0x00},

{0x23,0x00},

{0x24,0x38},

{0x25,0x04},

{0x2C,0x20},

{0x2D,0x80},

{0x30,0x06},

{0x31,0x80},

{0x34,0x8c},

{0x36,0x33},

{0x38,0x30},

{0x3A,0x03},

{0x3C,0x00},

{0x3D,0x00},

{0x3E,0x00},

{0x5B,0x00},

{0x93,0x24},

{0x94,0x80},

{0x5A,0x0D},

};

0 Ikram Haque 3 months ago in reply to GARETH OU

TI__Mastermind 22830 points

Hi Gareth,

1. With the color bar generator, the test pattern does not use the MIPI DSI clock.

I would recommend using this calculator tool to generate the register settings for initialization. You can enable color bar/ test pattern, or use normal video input. And you can compare the script with the driver script to check whether the register settings match.

Ikram Haque said:
Please use the calculator tool from this link to generate the I2C initialization script: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1382976/faq-sn65dsi8x-programming-tools

2. With normal video with MIPI DSI input, you can use REFCLK or use MIPI clock. The REFCLK frequency would need to be set to the specific frequency for your video (check calculator tool).

You can check whether REFCLK is detected or not from register 0x0A DPPLL_CLK_SRC

3. By using MIPI DSI CLK did you get correct video output as expected?

Best regards,
Ikram

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SN65DSI86: spec check