i.MX8M Resource Domain Controller - Core accessing Bus Master

[dilip]

Hello,

RDC  controls cores and bus masters access of memory and peripheral controllers. Cortex A53 and M4 are cores and USB Host controller is bus master.How to set the access permissions and domain if cortex M4 need to access USB Host controller? Couldn't find any PDAP register for USB Host. Can someone please guide me on this?

Regards,

Dilip

[art]

There are no PDAP registers for the USB controllers since they always operate as bus masters. The USB controller exchanges data with cores and other bus masters through a buffers assigned in shared memory.

Best Regards,
Artur

[dilip]

Hi Arthur,

Sorry. I didn't understood following explanation

"The USB controller exchanges data with cores and other bus masters through a buffers assigned in shared memory."

Does this mean USB Host controllers are always accessible by both M4 and A53 cores? I did following experiments on u-boot and still doesn't understand it fully.

Memory mapped address of Master assignment register for A53, M4, USB1 and 2 are following,

RDC_MDA0 - 0x303d0200

RDC_MDA1 - 0x303d0204

RDC_MDA19 - 0x303d024c

RDC_MDA20 - 0x303d0250

Using UBoot memory write commands, I assigned USB1 and USB2 to domain 1. By default, A53 and M4 are in domain zero. Then I executed "usb start" command to see whether A53 still able to access USB Host. It is working fine. Following are the corresponding serial console snapshot,

=> md 0 c
303d0200: 00000000 00000000 00000000 00000000 ................
303d0210: 00000000 00000000 00000000 00000000 ................
303d0220: 00000000 00000000 00000000 00000000 ................
=>
303d0230: 00000000 00000000 00000000 00000000 ................
303d0240: 00000000 00000000 00000000 00000001 ................
303d0250: 00000001 00000000 00000000 00000000 ................
=> usb start
starting USB...
USB0: Register 2000140 NbrPorts 2
Starting the controller
USB XHCI 1.10
USB1: Register 2000140 NbrPorts 2
Starting the controller
USB XHCI 1.10
scanning bus 0 for devices... 1 USB Device(s) found
scanning bus 1 for devices... 3 USB Device(s) found
scanning usb for storage devices... 0 Storage Device(s) found
=>

I am facing a specific problem when loading  M4 RTOS binary from u-boot. It is USB Host application and port status change interrupts are not getting triggered to M4 code when loaded via u-boot. It works fine, when loaded via JTAG. So I am kind of sure that since XHCI controllers are accessible from U-Boot, thats why M4 is not getting XHCI related events and interrupts.

Best Regards,

Dilip