Hi,
On 03/02/16 13:47, Arnd Bergmann wrote:
On Wednesday 03 February 2016 13:24:10 Zubair Lutfullah Kakakhel wrote:
Typically we treat those special registers as part of the device itself
and have a single device node for the AHCI controller and that one.
What is your reason for doing it differently here?
Two reasons
1- The hardware is like a proper split rather than additional hidden registers in
the same memory space.
2- Tons of devices in the field have the following DT node built in the bootloader.
uctl@118006c000000 {
compatible = "cavium,octeon-7130-sata-uctl";
reg = <0x11800 0x6c000000 0x0 0x100>;
...
sata: sata@16c0000000000 {
compatible = "cavium,octeon-7130-ahci";
reg = <0x16c00 0x00000000 0x0 0x200>;
...
};
};
The patch suggests a way to handle this.
Ok, fair enough. Also, you write in the binding that this is a bus
bridge, so this indeed matches what the hardware does, and that's ok.
Thank-you.
Does the bus bridge actually translate the entire 64-bit CPU MMIO space,
or is it possible that it only handles one device (or a couple of
them) with a fairly limited space?
This uctl is just for SATA devices.
Maybe it's better to represent it as a #address-cells=<1> in the
example, and have the child device appear at address 0 in there.
Possible in the example.
I'll update the example to
uctl@118006c000000 {
compatible = "cavium,octeon-7130-sata-uctl";
reg = <0x11800 0x6c000000 0x0 0x100>;
ranges; /* Direct mapping */
dma-ranges;
#address-cells = <1>;
#size-cells = <2>;
sata: sata@0 {
compatible = "cavium,octeon-7130-ahci";
reg = <0x16c00 0x00000000 0x0 0x200>;
interrupt-parent = <&cibsata>;
interrupts = <2 4>; /* Bit: 2, level */
};
};
For the machines that already ship a DT, that would not matter though,
it works either way.
Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
