SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Each local programming register is mapped twice inside the controller’s local target, with an offset of 0x1000 (4 KiB) between the two mappings.
The "low" mapping is the Data Interface (DIF) chip-select (CS) access. In DIF CS mode, some fields that are read-only (RO) over PCI become writable if PL bit PCIECTRL_PL_DBI_RO_WR_EN[0] CX_DBI_RO_WR_EN=0b1 (default). This access is used by the local host (e.g. BIOS) for the initialization of the PCI device, prior to PCI protocol startup (LTSSM enable). Fields and registers that are CS-sensitive are labeled (CS) in the Section 24.9.7.
The "high" mapping is the Data Interface (DIF) chip-select-2 (CS2) access. In DIF CS2 mode, some fields that are read-only (RO) over PCI or in DIF CS mode, become writable if PL bitfield PCIECTRL_PL_DBI_RO_WR_EN[0] CX_DBI_RO_WR_EN=0b1 (default). This access is also used by the local host for further initialization of the PCI device. Fields and registers that are CS2-sensitive are labeled (CS2) in the tables below.
The following important notes on accesses must be considered by user for device PCIe controller: