linux-kernel - Re: [PATCH] ARM: ux500: check platform in ux500_l2x0

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Message-ID: <CACRpkdaiKYCzb1t-eTEUSa5e5LupL3sqtE4GmFtWmaEOnRvhKQ@mail.gmail.com>
Date:	Wed, 26 Jun 2013 21:46:08 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Olof Johansson <olof@...om.net>
Cc:	"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: ux500: check platform in ux500_l2x0_init

On Wed, Jun 26, 2013 at 3:30 AM, Olof Johansson <olof@...om.net> wrote:

> Add compatible checks for ux500. This should probably be moved to generic
> DT-based probing whenever DT is populated instead, but until then at
> least don't panic all non-ux500 multiplatform machines.
>
> Signed-off-by: Olof Johansson <olof@...om.net>

> +       /* Ick. I wish there was a single compatible value to compare for,
> +        * but there isn't.
> +        */
> +       if (!of_machine_is_compatible("st-ericsson,u8500") &&
> +           !of_machine_is_compatible("st-ericsson,u8540") &&
> +           !of_machine_is_compatible("st-ericsson,u9500") &&
> +           !of_machine_is_compatible("st-ericsson,u8540"))
> +               return -ENODEV;

This is checking u8540 twice and does not account for snowball.

With new platforms coming we cannot just line up all possible
compat strings like this, we need to rely on the cpu_is* macro
to be reporting something sane, and I think it does.

What about just doing this:

>From da838c71fb32d63d7e28c14697702ff48088a09b Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@...aro.org>
Date: Wed, 26 Jun 2013 21:44:57 +0200
Subject: [PATCH] ARM: ux500: bail out on alien cpus

This makes the l2x0 initialization fail gracefully on non-ux500
systems.

Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
---
 arch/arm/mach-ux500/cache-l2x0.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-ux500/cache-l2x0.c b/arch/arm/mach-ux500/cache-l2x0.c
index f58615b..82ccf1d 100644
--- a/arch/arm/mach-ux500/cache-l2x0.c
+++ b/arch/arm/mach-ux500/cache-l2x0.c
@@ -42,7 +42,8 @@ static int __init ux500_l2x0_init(void)
     if (cpu_is_u8500_family() || cpu_is_ux540_family())
         l2x0_base = __io_address(U8500_L2CC_BASE);
     else
-        ux500_unknown_soc();
+        /* Non-Ux500 platform */
+        return -ENODEV;

     /* Unlock before init */
     ux500_l2x0_unlock();
--
1.8.1.4

Yours,
Linus Walleij
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