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SK-TDA4VM: MIPI

Cherry Zhou
Mastermind 22235 points
Part Number: SK-TDA4VM

Hi team,

Here's an issue from the customer may need your help:

Does SK-TDA4VM support 4lane for 4K resolution, 30fps MIPI data? And how is the pixel_rate calculated?

The customer has an external camera of 3856x2178, 30fps, raw12. They want to modify the drive of the imx219 to make the picture. However, the customer is not sure how the IMX219_pixel_rate in the drive and the link-frequencies in the device tree are calculated.

+#define IMX219_2LANE_PIXEL_RATE 182400000
+#define IMX219_4LANE_PIXEL_RATE 280800000
And what is the equation for the imx219 2lane and 4lane? 
Could you help check this case? Thanks.
Best Regards,
Cherry
  • 0
    TI__Genius 13655 points

    Hello Champs,

    Customer wanted to know below question which was he most cared. 

    Does SK-TDA4VM support 4lane for 4K resolution, 30fps MIPI data? 

    Thanks
    Regards,
    Shine

  • 0 in reply to Shine
    TI__Mastermind 31912 points

    Hi Shine,

    The example we have is using IMX390 (a 2MP camera) with the Fusion1 Rev C board, and it allows up to 8 cameras to be connected to the SK-TDA4VM board through the usage of virtual channels to two 4 lane CSI-2 interfaces: https://software-dl.ti.com/jacinto7/esd/processor-sdk-linux-sk-tda4vm/08_05_00/exports/docs/getting_started.html#imx390-raw-sensor

    As for the IMX219 connected through the RPi header, we only have validated two cameras connected, due to the limitations of the board only having two RPi headers.

    Lastly, I will need to check with our camera expert on how the pixel rate is calculated. Let me get back to you next week, as they are currently not in office.

    Regards,

    Takuma

  • 0 in reply to Takuma Fujiwara
    TI__Mastermind 31912 points

    Hi Shine,

    Just got information from our expert.

    • The equation for calculating pixel rate is pixel_clk_hz = sensor_data_rate_per_lane_Mbps * number_of_lanes / bits_per_pixel. For 2 lanes, we use the max sensor data rate of the camera which is 912Mbps at 10 bits per pixel. So, 182.4 = 912 * 2 /10.
    • For support on 4 channel 4K resolution, it seems it is not possible. To quote my colleague: "Assuming 2K height for this 4K line width and 16bpp, the data rate required for this resolution is around 4Gbps, so we can at max support 2 channels of this resolution. "

    The last thing that I still need confirmation from the team is how the link-frequencies in device tree is determined. 

    Regards,

    Takuma

  • 0 in reply to Takuma Fujiwara
    TI__Mastermind 31912 points

    Hi Shine,

    Apologies for the late reply, but it seems the number is calculated as (pixel_rate * bits_per_pixel) / (number_of_lanes * 2), meaning (182.4*10) / (2*2) = 456 MHz.

    Regards,

    Takuma