Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

[Rongrong Zou]

å 2016/1/5 0:34, Arnd Bergmann åé:
> On Tuesday 05 January 2016 00:04:19 Rongrong Zou wrote:
> > å 2016/1/4 19:13, Arnd Bergmann åé:
> > > On Sunday 03 January 2016 20:24:14 Rongrong Zou wrote:
> > > > å 2015/12/31 23:00, Rongrong Zou åé:
> > > > */
> > > >       compatible = "low-pin-count";
> > > >       device_type = "isa";
> > > >       #address-cells = <2>;
> > > >       #size-cells = <1>;
> > > >       reg = <0x0 0xa01b0000 0x0 0x10000>;
> > > >       ranges = <0x1 0x0 0x0 0x0 0x1000>;
> > > > /*
> > > > *  ranges is required, then i can get the IORESOURCE_IO <0xe4,4> from "reg = <0x1, 0x000000e4, 4>".
> > > > *
> > > > */
> > > >       ipmi_0:ipmi@000000e4{
> > > >               device_type = "ipmi";
> > > >               compatible = "ipmi-bt";
> > > >               reg = <0x1 0x000000e4 0x4>;
> > > > };
> > >
> > > This looks wrong: the property above says that the I/O port range is
> > > translated to MMIO address 0x00000000 to 0x00010000, which is not
> > > true on your hardware. I think this needs to be changed in the code
> > > so the ranges property is not required for I/O ports.
> >
> > Ranges property can set empty, but this means 1:1 translation. the I/O
> > port range is translated to MMIO address 0x00000001 00000000 to
> > 0x00000001 00000004, it looks wrong else. I wonder if anyone get legacy
> > I/O port resource from dts.
>
> As I said, nothing should really require the ranges property here, unless
> you have a valid IORESOURCE_MEM translation. The code that requires
> the ranges to be present is wrong.

I think the openfirmware(DT) do not support for those unmapped I/O ports, because I
must get resource by calling of_address_to_resource(), which have to call
pci_address_to_pio() when resource type is IORESOURCE_IO. I'm sorry I have no
better idea for this now. Maybe liviu can give me some opinions.

/**
 * of_address_to_resource - Translate device tree address and return as resource
 *
 * Note that if your address is a PIO address, the conversion will fail if
 * the physical address can't be internally converted to an IO token with
 * pci_address_to_pio(), that is because it's either called to early or it
 * can't be matched to any host bridge IO space
 */
int of_address_to_resource(struct device_node *dev, int index,
			   struct resource *r)

> > For ipmi driver, I can get I/O port resource by DMI rather than dts.
>
> No, the ipmi driver uses the resource that belongs to the platform
> device already, you can't rely on DMI data to be present there.

Ipmi has a lot of way to be discovered(ACPI, DMI, hardcoded, hot-add,
openfirmware and a few other), I think we just use one of them, not all of them.
It depend on vendor's hardware solution actually.


> 	Arnd
>
> .

Thanks,

Rongrong

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