Re: [PATCH] tty/serial: samsung: Add earlycon support
From: Rob Herring
Date: Sat Sep 20 2014 - 14:00:29 EST
On 09/20/2014 08:39 AM, Tomasz Figa wrote:
> Hi Alim,
> Please see my comments inline.
> On 16.09.2014 13:32, Alim Akhtar wrote:
>> Add earlycon support for the samsung serial port. This allows enabling
>> the samsung serial port for console when early_params are parse and processed.
>> Signed-off-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
>> Documentation/kernel-parameters.txt | 6 ++++++
>> drivers/tty/serial/Kconfig | 1 +
>> drivers/tty/serial/samsung.c | 17 +++++++++++++++++
>> 3 files changed, 24 insertions(+)
>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>> index 5ae8608..e01c0e5 100644
>> --- a/Documentation/kernel-parameters.txt
>> +++ b/Documentation/kernel-parameters.txt
>> @@ -936,6 +936,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>> must already be setup and configured. Options are not
>> yet supported.
>> + samsung,<addr>
There will only ever be 1 samsung uart? This is an ABI to some extent,
so you will be stuck with it.
>> + Start an early, polled-mode console on a samsung serial
>> + port at the specified address. The samsung serial port
>> + must already be setup and configured. Options are not
>> + yet supported.
> Couldn't you simply parse this from DT? I believe there is already code
> parsing stdout property in chosen node for earlycon purposes present in
> the kernel.
You should support both and it is just a OF_EARLYCON_DECLARE line to add.
> Anyway, we already had a patch for this in our internal tree, but it
> wasn't submitted because there was no support for early ioremap on ARM
> at that time. I haven't been following it since then (and I'm no longer
> at Samsung; Marek might be able to take this topic), is it already
No, but should be soonish. fixmap parts are being worked on by Kees.
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