I'm confused about the SD3.0 tuning.
In iMX8RM, there is a register "uSDHCx_TUNING_CTRL", bit 24 - STD_TUNING_EN. If the bit is set, standard tuning circuit and procedure enable. I want to know what is "standard tuning", how to do standard tuning. There should be "non-standard tuning", how to do "non-standard tuning"?
In register "uSDHCx_MIX_CTRL", bit 24 - AUTO_TUNE_EN; bit 22 - EXE_TUNE. How to do auto-tune? and how to do manual-tune? Do auto-tune have relation with "standard tuning" or "non-standard tuning".
By my understanding, there should be 4 possibility:
1. standard tuning by auto-tune;
2. standard tuning by manual-tune;
3. non-standard tuning by auto-tune;
4. non-standard tuning by manual-tune.
Is it correct? I really don't know how to do tuning. I need a note to describe how to do it.