How to use earlycon and earlyprintk on Samsung S3C24xx

[Woody Wu]

On Friday, February 26, 2016, <victorascroft at gmail.com> wrote:

> Hi,
>
> On 16-02-26 00:55:40, Woody Wu wrote:
> > Hi,
> >
> > It seems, at least in 4.4.2 kernel, earlyprintk parameter supports
> > something like 's3c24xx,<addr>'. But I dont know where to find out the
> addr
> > value of the first uart port on my *s3c2416* based board.  Can someone
> > please tell me?
> >
> > Also, I desire to know if the earlycon parameter supports the Samsung
> > S3C24xx uarts, if so, what should the value of the parameter look like?
>
> Have a look in the documentation here
> https://www.kernel.org/doc/Documentation/kernel-parameters.txt
>
> The kernels kernel-parameter.txt documentation file lists the supported
> drivers.
>
> Generally the UART0 port is used for debugging but I guess there is
> no such hard and fast rule.
>
> For your particular board, you can check which UART port is used
> as the debug serial console and then get the address for the concerned
> UART by checking the relevant dtsi file in
> arch/arm/boot/dts/s3c24xx.dtsi or perhaps one of the exynosX.dtsi files?
>
> UART0 port seems to have address of 0x50000000?
>
> Regards,
> Sanchayan.


Thanks for you pointing me to the dtsi files, very informational ! And,
yes, the uart0 address os 0x50000000 and I has made it work via
'earlyprintk=serial,0x50000000,115200'.  By the way, is this a physical
address or mmap-ed address?

>
> >
> > Thank in advance,
> >
> > -woody
> >
> >
> > --
> > Life is the only flaw in an otherwise perfect nonexistence
> >     -- Schopenhauer
> >
> > woody
> > public key at http://subkeys.pgp.net:11371 (narkewoody at gmail.com
> <javascript:;>)
>
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>

-- 
Life is the only flaw in an otherwise perfect nonexistence
    -- Schopenhauer

woody
public key at http://subkeys.pgp.net:11371 (narkewoody at gmail.com)
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