linux-kernel - Re: [PATCH] ARM: samsung: avoid racy early printk at bootup

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Date:	Wed, 5 Jun 2013 13:56:52 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Olof Johansson <olof@...om.net>
Cc:	Kukjin Kim <kgene.kim@...sung.com>,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Simon Glass <sjg@...omium.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Ben Dooks <ben-linux@...ff.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: samsung: avoid racy early printk at bootup

Olof,

On Tue, Jun 4, 2013 at 8:15 PM, Olof Johansson <olof@...om.net> wrote:
> This seems to be caused by not calling iotable_ini() in exynos_init_io()
> when a device tree is passed into the kernel, thus not setting up the
> mapping for the UART in that case.
>
> I think the solution is instead to map the uart earlier. The window of
> exposure is still there, but much smaller (and similar to how it always
> has been).
>
> In current upstream, if there is no map_io mach_desc entry at all,
> debug_ll_io_init() will be called on all platforms. Seems appropriate
> to call that explicitly before of_scan_flat_dt() in exynos_init_io()
> in this case.

Oh.  Ummm, right.  Yes, debug_ll_io_init() is exactly what's needed
here instead of all the complexity of what I proposed.  New patch
coming shortly.  Thanks!  :)

-Doug
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