[PATCH] exynos: Support big endian mode in secondary_startup

[PATCH] exynos: Support big endian mode in secondary_startup

[Mark Brown]

From: Victor Kamensky <victor.kamensky@linaro.org>

Exynos processors generally operate in little endian mode so their
bootloader and ROM will almost always operate in little endian mode.
This means that if a big endian kernel is run it must switch the CPU
into big endian mode after gaining control.

The generic secondary_startup that is called from exynos specific
secondary startup code will do the switch, but we need it to do earlier
because exynos specific secondary_startup code which runs first also
works with data that is big endian when the kernel is compiled for big
endian.

[Rewrote commit message. -- broonie]

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>
---
 arch/arm/mach-exynos/headsmp.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm/mach-exynos/headsmp.S b/arch/arm/mach-exynos/headsmp.S
index b54f9701e421..ac8364efb985 100644
--- a/arch/arm/mach-exynos/headsmp.S
+++ b/arch/arm/mach-exynos/headsmp.S
@@ -18,6 +18,11 @@
  * ready for them to initialise.
  */
 ENTRY(exynos4_secondary_startup)
+	/*
+	 * ROM code operates in little endian mode, when we get control we
+	 * need to switch it to big endian mode.
+	 */
+ARM_BE8(setend	be)
 	mrc	p15, 0, r0, c0, c0, 5
 	and	r0, r0, #15
 	adr	r4, 1f
-- 
2.0.1

[PATCH] exynos: Support big endian mode in secondary_startup

[Kukjin Kim]

Mark Brown wrote:
> 
> From: Victor Kamensky <victor.kamensky@linaro.org>
> 
> Exynos processors generally operate in little endian mode so their
> bootloader and ROM will almost always operate in little endian mode.
> This means that if a big endian kernel is run it must switch the CPU
> into big endian mode after gaining control.
> 
> The generic secondary_startup that is called from exynos specific
> secondary startup code will do the switch, but we need it to do earlier
> because exynos specific secondary_startup code which runs first also
> works with data that is big endian when the kernel is compiled for big
> endian.
> 
> [Rewrote commit message. -- broonie]
> 
> Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
> Signed-off-by: Mark Brown <broonie@linaro.org>

Hi Mark,

Basically, I have no objection on this, BTW is there any requirement to support
big endian on exynos stuff? Just wondering...

Thanks,
Kukjin

> ---
>  arch/arm/mach-exynos/headsmp.S | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm/mach-exynos/headsmp.S b/arch/arm/mach-exynos/headsmp.S
> index b54f9701e421..ac8364efb985 100644
> --- a/arch/arm/mach-exynos/headsmp.S
> +++ b/arch/arm/mach-exynos/headsmp.S
> @@ -18,6 +18,11 @@
>   * ready for them to initialise.
>   */
>  ENTRY(exynos4_secondary_startup)
> +	/*
> +	 * ROM code operates in little endian mode, when we get control we
> +	 * need to switch it to big endian mode.
> +	 */
> +ARM_BE8(setend	be)
>  	mrc	p15, 0, r0, c0, c0, 5
>  	and	r0, r0, #15
>  	adr	r4, 1f
> --
> 2.0.1

[PATCH] exynos: Support big endian mode in secondary_startup

[Mark Brown]

On Fri, Jul 25, 2014 at 01:45:14PM +0900, Kukjin Kim wrote:

> Basically, I have no objection on this, BTW is there any requirement to support
> big endian on exynos stuff? Just wondering...

We've been using it for testing within Linaro.  I don't know of any real
world users.
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[PATCH] exynos: Support big endian mode in secondary_startup

[Kukjin Kim]

Mark Brown wrote:
> 
> On Fri, Jul 25, 2014 at 01:45:14PM +0900, Kukjin Kim wrote:
> 
> > Basically, I have no objection on this, BTW is there any requirement to support
> > big endian on exynos stuff? Just wondering...
> 
> We've been using it for testing within Linaro.  I don't know of any real
> world users.

Mark, OK I see. I will apply.

Thanks,
Kukjin