On Sun, Aug 03, 2014 at 06:37:31PM -0300, Emilio L?pez wrote:

Hi Maxime,

El 03/08/14 a las 09:42, Maxime Ripard escibi?:

quoted

On Thu, Jul 31, 2014 at 06:28:05PM -0300, Emilio L?pez wrote:

quoted

Currently, some hardware revisions of sunxi SoCs need special care on
some blocks because of hardware differences and/or bugs. Unfortunately,
it is unfeasible to account for these issues directly when writing the
device tree, as SoC revision can vary between different units of the
same device. This commit introduces a place to adjust DT compatibles
as needed to work around said issues before devices are probed. To
demonstrate usage, two quirks are added for the PLL2 and audio codec
on sun4i.

Signed-off-by: Emilio L?pez <emilio@elopez.com.ar>
---

(...)

quoted

quoted

+static int __init sunxi_apply_quirks(void)
+{
+	if (of_machine_is_compatible("allwinner,sun4i-a10")) {
+		sun4i_pll2_quirk();
+		sun4i_codec_quirk();
+	}
+
+	return 0;
+}
+postcore_initcall(sunxi_apply_quirks)

Have you tested it? My guess is that it wolud have to run *much*
sooner, before of_platform_populate to be effective.

I have, I was able to break my UART with it :)

of_platform_populate() is called from arch/arm/kernel/setup.c on
arch_initcall. From include/linux/init.h

...
#define postcore_initcall(fn)           __define_initcall(fn, 2)
#define postcore_initcall_sync(fn)      __define_initcall(fn, 2s)
#define arch_initcall(fn)               __define_initcall(fn, 3)
...

So it should be fine.

Hmmm, right.

I was under the impression it was done sooner, but I was wrong,
obviously.

Still, the machine init callback has the advantage of being run only
on the current machine, not in every case.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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