topic Re: Getting continuous clock on eMMC (i.MX6Q custom board) in i.MX Processors

Getting continuous clock on eMMC (i.MX6Q custom board)

pratik_manvar — Tue, 01 Oct 2019 13:19:36 GMT

Hi NXP team,

We are using i.MX6 Quad custom board. In that, the eMMC card is connected on SDIO3 interface.

DTS entry for eMMC is as below:

---------------------------------------------------------

/* eMMC */
&usdhc3 {
   pinctrl-names = "default";
   pinctrl-0 = <&pinctrl_emmc>;
   no-1-8-v;
   non-removable;
   keep-power-in-suspend;
   enable-sdio-wakeup;
   status = "okay";
};

pinctrl_emmc: emmc {
fsl,pins = <
   MX6QDL_PAD_SD3_RST__SD3_RESET 0x1b0b0
   MX6QDL_PAD_SD3_CMD__SD3_CMD 0x1b0b0
   MX6QDL_PAD_SD3_CLK__SD3_CLK 0x1b0b0
   MX6QDL_PAD_SD3_DAT0__SD3_DATA0 0x1b0b0
   MX6QDL_PAD_SD3_DAT1__SD3_DATA1 0x1b0b0
   MX6QDL_PAD_SD3_DAT2__SD3_DATA2 0x1b0b0
   MX6QDL_PAD_SD3_DAT3__SD3_DATA3 0x1b0b0
   MX6QDL_PAD_SD3_DAT4__SD3_DATA4 0x1b0b0
   MX6QDL_PAD_SD3_DAT5__SD3_DATA5 0x1b0b0
   MX6QDL_PAD_SD3_DAT6__SD3_DATA6 0x1b0b0
   MX6QDL_PAD_SD3_DAT7__SD3_DATA7 0x1b0b0
>;
};

---------------------------------------------------------

We are getting continuous clock on eMMC. So, we want to stop the continuous clock on eMMC for EIM reduction.

The clock should only come on any read/write operation on eMMC.

Please let us know, how we can stop continuous clock on eMMC?

Thanks.

Regards,

Pratik Manvar

Re: Getting continuous clock on eMMC (i.MX6Q custom board)

jamesbone — Thu, 10 Oct 2019 14:50:37 GMT

Hello

Unfortunately this is not going to be possible, since the EMMC it is the boot option for your design, you need to keep the Media of the source code always ON, if you are experiencing EMC issues, I think you need to reconsider something in the layout or review if any cover can be used instead of shutting down the main media access for the system.

Re: Getting continuous clock on eMMC (i.MX6Q custom board)

pratik_manvar — Fri, 11 Oct 2019 05:21:59 GMT

Hello James,

Thanks for your response.

Actually, we are not using eMMC for boot option. It is only used for internal storage device. So, we are expecting that, clock should only come on any read/write operation on eMMC.

Thanks,

Pratik Manvar

Re: Getting continuous clock on eMMC (i.MX6Q custom board)

pratik_manvar — Wed, 16 Oct 2019 07:50:26 GMT

Hello NXP team and James,

We have enabled below kernel configuration and able to rid of from the continuous clock on eMMC.

-----------------------------------------------------------------------------------------------

CONFIG_MMC_CLKGATE:

This will attempt to aggressively gate the clock to the MMC card.

This is done to save power due to gating off the logic and bus

noise when the MMC card is not in use. Your host driver has to

support handling this in order for it to be of any use.

-----------------------------------------------------------------------------------------------

Can you please confirm, if this is the right way to stop the continuous clock on eMMC?

Thanks,

Pratik Manvar

Re: Getting continuous clock on eMMC (i.MX6Q custom board)

jamesbone — Fri, 18 Oct 2019 18:14:17 GMT

I can confirm that it is a way to gate the clock, so you can stop them.