i.MX8Q - Enabling USB Host for M4 Access From Uboot

[dilip]

I am using a i.MX8Q based board for developing an RTOS application that run on M4 core. Application uses USB Host port for downstream device enumeration. But some strange issue is found when the app binary is loaded via u-boot. USB Host interrupts are not getting invoked in M4 application and device connection to USB host ports are not detected. Application is executing and I can see prints on serial terminal corresponding to M4

But if the same binary is loaded to DDR via JTAG and executed, there are no issues and USB host interrupts are getting triggered.

I am suspecting following, U-Boot is somehow blocking access of Cortex M4's USB Host access via RDC or some other mechanisms

Can someone please guide me how to proceed? I am looking a way to use "mw" u-boot command to make necessary register settings before  "bootaux"

Best Regards,

Dilip

[dilip]

Hi Igor,

Any good write ups on RDC other than IMX8MDQLQRM.pdf?

Best Regards,

Dilip

[igorpadykov]

Hi dilip

opposite to previous i.MX processors in i.MX8Q access to peripherals is

performed through SCU and its APIs, described in SCFW Porting Kit​

One can try to assign USB to M4 partition using example on below link:

"Modifying default configuration"

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/System-Controller-Firmware-101-Resource-...

Best regards
igor

[dilip]

Hi Igor,

Sorry for the mis-information. The imx core on ref board is i.MX8MQ. Can you please guide for this?

Best Regards,

Dilip

[igorpadykov]

Hi Dilip

for i.MX8MQ one can try to set permissions in RDC :

https://source.codeaurora.org/external/imx/imx-atf/tree/plat/imx/imx8m/imx_rdc.c?h=imx_5.4.24_2.1.0

Best regards
igor

[dilip]

Hi Igor,

Is there whitepaper or write up on RDC usage? Have found only IMX8MDQLQRM.pdf  that explains RDC.

Best Regards,

Dilip