[PATCH/RFC 0/2] serial: samsung: add support for early console

Marek Szyprowski m.szyprowski at samsung.com
Tue Sep 23 06:08:41 PDT 2014


On 2014-09-23 14:53, Alim Akhtar wrote:
> Hi Marek,
> On Mon, Sep 22, 2014 at 6:44 PM, Marek Szyprowski
> <m.szyprowski at samsung.com> wrote:
>> Hello,
>> This patchset adds support for early console defined in device tree. As
>> an example, DTS files for all Exynos4 based machines are updated with
>> the correct value for common chosen/sdtout property.
>> To get it fully functional additional improvements (support for
>> early_ioremap) are needed in early console code.
> Is these really tested?

I've tested it on Exynos4412 based OdroidU3 board. It works fine, although
early console is not initialized as early as it might be. That's the only
drawback, besides that it works fine.

> So that mean we need to wait till __ioremap__ support available for ARM.
> How to take this forward then? Here is a platform (exynos7) which
> needs earlycon support for debugging some of the early core things and
> ARM64 has ioremap support as well. There is no reason why we should
> hold earlycon support for exyons7.

I prefer to simply merge the patch as is. Once early con gets full
functionality, all required samsung code will be already in then.

> I see two solution here:
> 1> How about re-spin patch-1 which will just add ealrycon support for
> __exynos4210__ serial type only? And rest of the types can be added as
> incremental patches, as and when ioremap for ARM available.
> Atleast this approch will solve exynos7 problem of not having earlycon support.
> And This patch can be tested on exynos7 (I can do that).
> 2> Take  my patch which is working and tested for exynos7 and can be
> easily extended and generalized when ioremap for ARM is available.
> My preference would be the the first one.
> Let me know your thoughts please.
> In case you are ok with 1st approach, can you please re-spin patch1
> with needed changes?

Best regards
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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