SDHC register TUNING_CTR (offset 0xCC)was not found in i.MX8X Reference Manual

[anguschen]

Hi, team

I can not find the description for the SDHC register TUNING_CTR (offset 0xCC) in RM Rev.0(05/2020).

Is this register undocumented or removed?

Thank you!

[IvanRuiz]

Hello,

Could you please be more specific? Where have you seen this register before, in which document of which products? I cannot find it in the reference manual of the i.MX 8X as you mentioned.

BR,

Ivan.

[anguschen]

Hello, Ivan

Thanks for help. Also I can not find any information about the register in the reference document.

But I found the definition in the BSP source code offered by QNX.

According to the description, this register should be related with the  DLL tunning for eMMC.

I think this register was not publicly documented.

Could you please check this internally?

Thank you!

[joanxie]

yes, I couldn't find this in the RM either, but maybe you can refer to the bsp, which defines this, and use this as the bsp mentions:

"https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/mmc/host/sdhci-esdhc-imx.c?h=imx_5...

#define ESDHC_TUNING_CTRL		0xcc
#define ESDHC_STD_TUNING_EN		(1 << 24)
/* NOTE: the minimum valid tuning start tap for mx6sl is 1 */
#define ESDHC_TUNING_START_TAP_DEFAULT	0x1
#define ESDHC_TUNING_START_TAP_MASK	0x7f
#define ESDHC_TUNING_CMD_CRC_CHECK_DISABLE	(1 << 7)
#define ESDHC_TUNING_STEP_MASK		0x00070000
#define ESDHC_TUNING_STEP_SHIFT		16

[joanxie · Accepted solution]

refer to the bsp code, it seems

the bit24 is Standard tuning circuit and procedure enable
This field is used to enable standard tuning circuit and procedure.

bit 16-18:TUNING_STEP
The increasing delay cell steps in tuning procedure

bit 7:

Disable command check for standard tuning
Writing 1 to this field disables command check (command CRC, CMD end bit error, and CMD index error
or CMD timeout error) for standard tuning flow after each tuning command is sent

bit0-6:

Tuning start
The start delay cell point when send first CMD19 in tuning procedure

[anguschen]

Thanks.