On Wed, May 14, 2014 at 2:00 AM, Maxime Ripard
[off-list ref] wrote:

Hi Stephen,

On Tue, May 13, 2014 at 03:47:32PM -0700, Stephen Boyd wrote:

quoted

On 05/13, Matthias Brugger wrote:

quoted

diff --git a/arch/arm/mach-mediatek/mediatek.c b/arch/arm/mach-mediatek/mediatek.c
new file mode 100644
index 0000000..73dfb05
--- /dev/null
+++ b/arch/arm/mach-mediatek/mediatek.c

@@ -0,0 +1,32 @@
+/*
+ * Device Tree support for Mediatek SoCs
+ *
+ * Copyright (c) 2014 MundoReader S.L.
+ * Author: Matthias Brugger <matthias.bgg@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/of_platform.h>
+#include <linux/irqchip.h>
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+static const char * const mediatek_board_dt_compat[] = {

__initconst?

quoted

+   "mediatek,mt6589",
+   NULL,
+};
+
+DT_MACHINE_START(MEDIATEK_DT, "Mediatek Cortex-A7 (Device Tree)")
+   .dt_compat      = mediatek_board_dt_compat,
+MACHINE_END

You shouldn't need this file at all if the platform is part of
the multi-platform kernel.

From a technical point of view, you don't. But it's interesting to
keep it mostly for two things:
  - You get to see the platform name in /proc/cpuinfo

We should be getting this string from model or top-level compatible
string in the dtb. I did a patch to do just this [1], but people did
not like removing this string. We should really decide if getting rid
of machine descriptors is a goal or not.

We should at least make things such that the cpuinfo string does not
change on new platforms based on whether they have a machine desc or
not.

  - If you ever need to add platform quirks, it's already there

That is a weak argument when usually we add things as they are needed.

Rob

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2013-November/208878.html