Re: [DO NOT MERGE v5 11/37] pci: pci-sh7751: Add SH7751 PCI driver

Linus Walleij
2023-12-05T21:48:59Z

On Tue, Dec 5, 2023 at 2:26 PM Arnd Bergmann <arnd@arndb.de> wrote:
> On Tue, Dec 5, 2023, at 10:45, Yoshinori Sato wrote:

> > + if (of_property_read_u32_array(pdev->dev.of_node,
> > + "renesas,memory", memory, 2) < 0) {
> > + /*
> > + * If no memory range is specified,
> > + * the entire main memory will be targeted for DMA.
> > + */
> > + memory[0] = memory_start;
> > + memory[1] = memory_end - memory_start;
> > + }
>
> There is a generic "dma-ranges" proerty for describing
> which memory is visible by a bus.

It's really a headache to use, so I put a bit of documentation here:
https://elinux.org/Device_Tree_Usage#PCI_DMA_Address_Translation

Yoshinoro, you can look at these bindings and drivers that use
dma-ranges for help:
Documentation/devicetree/bindings/pci/intel,ixp4xx-pci.yaml
drivers/pci/controller/pci-ixp4xx.c
Documentation/devicetree/bindings/pci/faraday,ftpci100.yaml
drivers/pci/controller/pci-ftpci100.c

Yours,
Linus Walleij