Dear Sir or Madam,
I have got the below answer about Variable delay function of SD specification in i.MX6 series.
"CMD19 is supported for both SDR-104 and SDR-50."
But, refer to Table 67-6. Commands for MMC/SD/SDIO Cards (P.5618) in IMX6DQRM(Rev.2).
"CMD19 is Reserved"
And then, refer to uSDHCx_INT_STATUS field descriptions(P.5654).
"Tuning Pass:(only for SD3.0 SDR104 mode)
Current CMD19 transfer is done successfully. That is, current sampling point is correct."
Is the tuning function supporting for both SDR-104 and SDR-50?