[PATCH] ARM: dts: imx: Pass an empty 'chosen' node

[Javier Martinez Canillas]

[adding Pali who first reported this issue]

Hello Pali,

On 12/19/2016 06:30 PM, Fabio Estevam wrote:
> Hi Uwe,
> 
> On Mon, Dec 19, 2016 at 4:41 PM, Uwe Kleine-König
> <u.kleine-koenig at pengutronix.de> wrote:
> 
>> wouldn't it be better to fix the decompressor code to eventually create
>> the /chosen node when it doesn't exist?
>
> Thanks for the suggestion.
> 
> I don't have a Barebox setup handy, but would the following change fix
> it as you propose?
>

Could you test Fabio's patch with NoLo to see if it fixes your issue?

I also think it makes more sense for Linux to create the "chosen" node
if not present since this is a requirement due a Linux implementation
detail.

Forcing to have a "chosen" node in dts leaks this implementation detail
since the ePAPR document says that the "chosen" node should be optional.
 
> --- a/arch/arm/boot/compressed/atags_to_fdt.c
> +++ b/arch/arm/boot/compressed/atags_to_fdt.c
> @@ -66,13 +66,21 @@ static uint32_t get_cell_size(const void *fdt)
>         return cell_size;
>  }
> 
> -static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
> +static int merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
>  {
>         char cmdline[COMMAND_LINE_SIZE];
>         const char *fdt_bootargs;
>         char *ptr = cmdline;
> +       int chosen_off;
>         int len = 0;
> 
> +       /* find or add chosen node */
> +       chosen_off = fdt_path_offset(fdt, "/chosen");
> +       if (chosen_off == -FDT_ERR_NOTFOUND)
> +               chosen_off = fdt_add_subnode(fdt, 0, "chosen");
> +       if (chosen_off < 0)
> +               return chosen_off;
> +
>         /* copy the fdt command line into the buffer */
>         fdt_bootargs = getprop(fdt, "/chosen", "bootargs", &len);
>         if (fdt_bootargs)
> 

Best regards,
-- 
Javier Martinez Canillas
Open Source Group
Samsung Research America