iMX8MM PCIE DMA and iATU register

kuanlun_chiu · ‎09-22-2020

In imx_5.4.24_2.1.0 Linux, I want to enable PCIE EP mode for our dev board of iMX8MM.

I check DMA and iATU register definition in below two files.

#define DMA_REG_OFFSET 0x970 in drivers/pci/controller/dwc/pci-imx6.c

#define PCIE_ATU_VIEWPORT 0x900 in drivers/pci/controller/dwc/pcie-designware.h

But I cannot find any description about these two register offset in iMX8MM processor reference manual (IMX8MMRM.pdf).

Are these two register offset in iMX8 the same as iMX6?

kuanlun_chiu · ‎09-29-2020

Hi igor,

But I cannot find any information about PCIE DMA & iATU registers in i.MX Linux Reference Manual.

And after tracing imx pcie driver, I found actual DMA & iATU offset are defined as below.

Why there is no iMX docs describe these offset?

#define DEFAULT_DBI_ATU_OFFSET (0x3 << 20) (In drivers/pci/controller/dwc/pcie-designware.c)

#define DMA_UNROLL_CDM_OFFSET (0x7 << 19) (In drivers/pci/controller/dwc/pci-imx6.c)

igorpadykov · ‎09-29-2020

Hi kuanlun_chiu

>Are these two register offset in iMX8 the same as iMX6?

yes, as driver (drivers/pci/controller/dwc/pci-imx6.c) is the same

as described in sect.4.8 PCI Express Root Complex

>But I cannot find any information about PCIE DMA & iATU registers in i.MX Linux Reference Manual.

since PCIe module is the same as in i.MX6Q, one can look at i.MX6Q Reference Manual.

Best regards
igor

igorpadykov · ‎09-28-2020

Hi kuanlun_chiu

>Are these two register offset in iMX8 the same as iMX6?

yes, as driver (drivers/pci/controller/dwc/pci-imx6.c) is the same

as described in sect.4.8 PCI Express Root Complex

Best regards
igor