Re: [PATCH v4 2/8] arm64: dts: exynos: Add dts files for 64-bit Exynos5433 SoC

Arnd Bergmann
2015-02-25T15:07:20Z

On Tuesday 24 February 2015 20:04:17 Chanwoo Choi wrote:
> On 02/24/2015 06:48 PM, Arnd Bergmann wrote:
> > On Tuesday 24 February 2015 17:52:01 Chanwoo Choi wrote:
> >>
> >> But, I have a question.
> >> If we put the aliases into the board dts file instaed of SoC dtsi,
> >> each board dts file may use the different alias name about same phandle.
> >
> > Yes, that is the idea. In particular with the uarts, the intention is
> > that the numbering of the device nodes in /dev is the same that is
> > printed on the board (if any), which may be different from the numbering
> > internal to the SoC.
>
> I check the uart device with Exynos5433 SoC based on Linux 4.0-rc1
> If some board use the serial_0 and serial_3 as following in board dtsi,
>
> &serial_0 { --> UART 0 device
> status = "okay";
> };
>
> &serial_3 { --> UART 3 device
> status = "okay";
> };
>
> The serial core driver create the follwoing /dev/ttySACx device node
> by using the number of alias. It maintain the same device number of internel to the SoC.
>
> root@localhost:~# ls /dev/ttySAC
> ttySAC1 ttySAC3
>

I'm not completely following. So you have set the serial1 alias to
the &serial_0 device node and serial3 to &serial_3?

Why not use serial0=&serial_0 and serial1=&serial_3? Does the serial0
alias have a special meaning?

Arnd