Which peripherals on the IMX6-SDB/SDP need care at warm boot in general?

[torus1000]

Hi,

For some reasons, several peripheral powers keep alive during mem(state retaintion) mode.
Actually I found following description in the imx6qdl-sabresd.dtsi which expected keep-power.

> &usdhc4 {
> ...
> keep-power-in-suspend;
> status = "okay";
> };

Based on that I tried to shutdown power with modified PMIC driver(pfuz100-regulator.c).
Then I could see SW4 supply stopped when wrote 0x04 to SW4MODE register.
My question for the next step is following:

Which peripherals on the i.MX6 Sabre-SD board need special care at warm boot?

I guess LCD or LVDS need no initialization.
How about eMMC/SD, NOR, Audio(WM8962), ETHER-PHY or USB?

Can anyone help me?

[Yuri]

Hello,

 NXP recommends  to implement total system POR, via external circuit.

For more details please create request (ticket).

https://community.nxp.com/docs/DOC-333731 

Regards,

Yuri.

[weidong_sun]

Hello torus,

     I have tested POR pin of i.MX6 for many times: connecting a button on the pin, only reset processor, don't care about other external devices. And board can normally boot, no problem.  The test is warm reset (warm reboot)

     so I think you if your external devices doesn't have special requirement on reset, you don't need to care about it.

Have a nice day!

TIC Weidong sun

[torus1000]

Thank you for replying. It was very valuable.