From AM335X Technical Reference Manual Table 9-1. Pad control register filed descriptions, we can get bit 3 meaning. 0 pullup/pulldown disable 1 pullup/pulldown enable But from uboot and kenel codes we can get #define PULLUDEN (0x0 << 3) /* Pull up or pull down enabled */ #define PULLUDDIS (0x1 << 3) /* Pull up or pull down disabled */ File: mux.c in uboot. /* bit 3: 0 - enable, 1 - disable for pull enable */ #define AM33XX_PULL_DISA (1 << 3) #define AM33XX_PULL_ENBL (0 << 3) File:mux.h in linux I don’t know which one is right? Code or datasheet.
