About the change of i.MX6 PCIe RC and EP

[george]

Dear All,

We want to use PCIe on original OS.

The setting value is investigated by dump registers on Linux.

RM has the following descriptions about the switching of RC and EP.

Page 2052 in Applications Processor Reference Manual (Document Number: IMX6SDLRM Rev. 1, 04/2013) :

Section 37.4.13 GPR12 (IOMUXC_GPR12)

Address: 20E_0000h base + 30h offset = 20E_0030h

Field : 15－12  DEVICE_TYPE

Description :

PCIe_CTL - Device/Port Type. Indicates the specific type of

this PCI Express Function (EP or RC)

DEVICE_TYPE field values 0011-1111 are reserved.

• 0000 PCIE_EP － EP Mode
• 0010 PCIE_RC － RC Mode

However, the dump value was "0100"

root@wandboard:~# lspci

00:00.0 PCI bridge: Device 16c3:abcd (rev 01)

01:00.0 PCI bridge: Texas Instruments XIO2001 PCI Express-to-PCI Bridge

02:00.0 RAM memory: XXXXXXXXXXXXXXXXXXXXXXXXXXXXX. Device 8002 (rev 01)

root@wandboard:/# ./unit_tests/memtool 20E0030 10

E

Reading 0x10 count starting at address 0x020E0030

0x020E0030:  0F004490 0593A046 00000000 00000000

0x020E0040:  00000000 00000000 00000000 00000003

0x020E0050:  00000003 00000005 00000005 00000005

0x020E0060:  00000005 00000005 00000005 00000005

root@wandboard:~#

Please let me know what kind of meaning this value has.

Best Regard,

George

[b47504 · Accepted solution]

• 0000b: PCI Express Endpoint device

• 0001b: Legacy PCI Express Endpoint device

• 0100b: Root Port of PCI Express Root Complex

Device_type 0100b causes the DM core to operate in RC mode.

You can check page 4198 line 1-2 on sdl rm:

The core is not in RC mode (applies to DM product only).

That is, device_type[3:0] is not 4'b0100.

[george]

Yuan,

Please let me confirm.

That is, the following description in RM Page 2052 is wrong.

These descriptions should be corrected.

Is my understanding correct?

BR

George