Re: [PATCH 11/12] ARM: dts: add support for Vybrid running on Cortex-M4

[Stefan Agner <stefan@agner.ch>]

On 2014-12-17 13:31, Arnd Bergmann wrote:
> On Wednesday 17 December 2014 00:41:33 Stefan Agner wrote:
>> On 2014-12-03 12:03, Arnd Bergmann wrote:
>> > On Wednesday 03 December 2014 01:12:10 Stefan Agner wrote:
>> >> diff --git a/arch/arm/boot/dts/vf610m4-colibri.dts b/arch/arm/boot/dts/vf610m4-colibri.dts
>> >> new file mode 100644
>> >> index 0000000..051ee0f
>> >> --- /dev/null
>> >> +++ b/arch/arm/boot/dts/vf610m4-colibri.dts
>> >> @@ -0,0 +1,52 @@
>> >> +/*
>> >> + * Device tree for Colibri VF61 Cortex-M4 support
>> >> + *
>> >> + * Copyright 2014 Stefan Agner
>> >> + *
>> >> + * This program is free software; you can redistribute it and/or modify
>> >> + * it under the terms of the GNU General Public License as published by
>> >> + * the Free Software Foundation; either version 2 of the License, or
>> >> + * (at your option) any later version.
>> >> + */
>> >> +
>> >> +/dts-v1/;
>> >> +#include "vf610m4.dtsi"
>> >> +
>> >> +/ {
>> >> +       model = "VF610 Cortex-M4";
>> >> +       compatible = "fsl,vf610m4";
>> >> +
>> >> +       chosen {
>> >> +               bootargs = "console=ttyLP2,115200 ihash_entries=64 dhash_entries=64 earlyprintk clk_ignore_unused init=/linuxrc rw";
>> >> +       };
>> >> +
>> >
>> > Starting with v3.19, you should be able to use the earlycon framework on
>> > arm32, so it would be better to replace earlyprintk with earlycon here
>> > and add a stdout-path property in chosen that points to the console
>> > uart.
>>
>> I started to implement earlycon support, but something currently fails
>> when earlycon tries to map the UART registers:
>> [    0.000000] earlycon_map: Couldn't map 0x40027000
>>
>> I traced the issue a bit further down and found that get_vm_area_caller
>> returns NULL (in __arm_ioremap_pfn_caller). This happend on Linus master
>> as of today (2dbfca5a181973558277b28b1f4c36362291f5e0). Do I miss
>> something here?
> 
> Hmm, I fear the arm32 FIX_EARLYCON_MEM support ended up not making it
> into 3.19 after all. :(

Is it because early_ioremap and fixmap still missing for arm32?
According to Rob's patchset from spring fixmap is required, there is
something in this tree:
https://git.kernel.org/cgit/linux/kernel/git/robh/linux.git/log/?h=arm-fixmap

--
Stefan