The data pin about sd card can't be pull down or up without sd card, why?

Autonomous Vehicles DRIVE PX 2 DRIVE Hardware
1

When I insert the SD card , SDCARD_DAT0_POL, SDCARD_DAT1_POL, SDCARD_DAT2_POL, SDCARD_DAT3_POL can be pull down or up, but if there is no SD card, these pin would can’t control. Why?

2

Dear Tegra_GPIO_A,

DrivePX2 has no SD card slot.
Could you let me know this topic is for DrivePX2? Thanks.

3

The paltform is Jetson TX1.

4

Dear Tegra_GPIO_A,
Could you post this question in Jetson TX1 forum.