imx8mp USB_ID and USB boot questions

[diegoperez]

Hi,

I have some questions about USBs of the imx8mp:

In the EVK schematic there is a note that says “USB1_DNU, USB2_DNU are not functional, if USB ID function is needed, use common GPIO”.

• It will be solved in the future?
• This means that any GPIO can be used?
• The GPIO selected need to be configured in the device tree as USB_ID?

In the ROM USB boot (download mode), datasheet says:

“

21.7 USB boot

ROM supports both of the USB ports on the chip for boot purposes. Only one port can be

selected as the boot connection. The port that is active first wins the selection.

USB boot in ROM code works as a HID device. ROM takes USB as a normal boot

device. …

”

• I suppose the connection for USB boot mode (download mode) is USB 2.0 using only “usb_d_p” and “usb_d_n” signals even if a complete USB type c connector will be used with USB 3.0 signals. Am I right?
• ROM Boot code always put the two USBs as OTG device and wait for enumeration?
• The first USB OTG that will be enumerated wins the selection?

Thanks.

[igorpadykov]

Hi Diego

• It will be solved in the future?

currently no such known plans

• This means that any GPIO can be used?

yes

• The GPIO selected need to be configured in the device tree as USB_ID?

yes

• I suppose the connection for USB boot mode (download mode) is USB 2.0 .. Am I right?

not, ROM serial downloader uses a high-speed USB

• ROM Boot code always put the two USBs as OTG device and wait for enumeration?

yes

• The first USB OTG that will be enumerated wins the selection?

yes

Best regards
igor

[diegoperez]

@igorpadykov thanks for your reply.

I want to use USB2 to connect a USB2.0 HUB via USB2_D_P and USB2_D_N, I do not need USB 3.0 PHY (USB2_TX and USB2_RX). So, USB2 has not chance to enter into download mode.

USB1 will be connected to microUSB AB OTG, so only USB1_D_P and USB1_D_N will be used.

I have a doubt according to your answer:

“I suppose the connection for USB boot mode (download mode) is USB 2.0 .. Am I right?

not, ROM serial downloader uses a high-speed USB”

• Can my USB1 enter download mode (USB BOOT) using only USB1_D_P and USB1_D_N signals?
• If the 3.0 PHY signals are not used, can they be float?

Thanks and BR.

Diego.

[igorpadykov · Accepted solution]

>I have a doubt according to your answer:

>“I suppose the connection for USB boot mode (download mode) is USB 2.0 .. Am I right?

USB 2.0 also can be used. If only USB2.0 is used, USB3.0 signals can be left open.

Best regards
igor