Re: [PATCH v3 08/10] tegra: add generic debug UART support

[Lucas Stach <dev@lynxeye.de>]

Am Montag, den 08.04.2013, 15:46 +0400 schrieb antonynpavlov@gmail.com:
> On Mon, 08 Apr 2013 12:57:26 +0200
> Lucas Stach <dev@lynxeye.de> wrote:
> 
> > Hi Antony,
> > 
> > Am Freitag, den 05.04.2013, 00:32 +0400 schrieb antonynpavlov@gmail.com:
> > > On Tue,  2 Apr 2013 08:19:10 +0200
> > > Lucas Stach <dev@lynxeye.de> wrote:
> > > 
> > > > ODMdata tells us which UART to use for debugging purposes. This is
> > > > agreed upon in both the upstream Linux kernel and U-Boot, so do it the
> > > > same way in barebox.
> > > 
> > > This patch disables serial console on my Toshiba AC100.
> > > 
> > Hm that's unfortunate, but I already suspected that your ODMdata might
> > be wrong.
> > What happens if you don't remove the serial init in your board? Do you
> > get a duplicate serial, or just your board defined one? If it still
> > works for you this way, we might take this as a compromise for now.
> 
> IMHO, the right way is to get of_serial.c from linux and put some records 
> like this 
>  uarta: serial@70006000 {
>                 compatible = "nvidia,tegra20-uart";
>                 reg = <0x70006000 0x40>;
>                 reg-shift = <2>;
>                 interrupts = <0 36 0x04>;
>                 nvidia,dma-request-selector = <&apbdma 8>;
>                 clocks = <&tegra_car 6>;
>                 status = "disabled";
>   };
> 
> to arch/arm/dts/tegra20.dtsi.
> 

No, this doesn't help with the decision which UART barebox should use
for it's output. This is a configuration option and therefore not
allowed to reside in the DT, so NVIDIA decided to put this information
into the ODMdata. Both U-Boot and the Linux kernel(for earlyconsole) use
the information stored in this location.

You can always activate more consoles from board code or DT, but the
first/debug console should IMHO be handled the same way it's done in
Linux.

Regards,
Lucas


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