netdev - Re: Keystone 2 boards boot failure

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Date:	Wed, 03 Feb 2016 17:35:17 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	"Franklin S Cooper Jr." <fcooper@...com>
Cc:	m-karicheri2@...com, netdev@...r.kernel.org, w-kwok2@...com,
	davem@...emloft.net
Subject: Re: Keystone 2 boards boot failure

On Tuesday 02 February 2016 19:19:13 Franklin S Cooper Jr. wrote:
> On 02/02/2016 05:26 PM, Arnd Bergmann wrote:
> > On Tuesday 02 February 2016 16:59:34 Franklin Cooper wrote:
> >> On 02/02/2016 03:26 PM, Arnd Bergmann wrote:
> >>> On Tuesday 02 February 2016 15:01:33 Franklin S Cooper Jr. wrote:
> >> Keystone 2 devices are little-endian 32-bit devices.
> > I meant the kernel you are running on it, not the hardware.
> > You should always be able to run both a big-endian kernel and
> > a littl-endian kernel on any ARMv7 machine, and a couple of
> > platforms use 64-bit physical addresses even on 32-bit machines
> > (with the normal 32-bit instruction set).
> 
> I'm not sure if Keystone 2 devices support this or if we
> have support for this. I'll have to double check.

Don't worry about it, there is nothing you need to check:

As I said, all ARMv7 *hardware* can be run in either mode, and
that includes Keystone 2.

As for the kernel, it's obvious that nobody tried to run
a Keystone based machine with a big-endian kernel, or they
would have run into the broken network driver.

I believe you also require this patch, unless the firmware is
clever enough to figure out endianess by itself (very unlikely)

diff --git a/arch/arm/mach-keystone/keystone.h b/arch/arm/mach-keystone/keystone.h
index 33eaa037af5a..016ae7644e73 100644
--- a/arch/arm/mach-keystone/keystone.h
+++ b/arch/arm/mach-keystone/keystone.h
@@ -16,7 +16,7 @@
 #ifndef __ASSEMBLER__
 
 extern const struct smp_operations keystone_smp_ops;
-extern void secondary_startup(void);
+extern void keystone_secondary_startup(void);
 extern u32 keystone_cpu_smc(u32 command, u32 cpu, u32 addr);
 extern int keystone_pm_runtime_init(void);
 
diff --git a/arch/arm/mach-keystone/platsmp.c b/arch/arm/mach-keystone/platsmp.c
index 5665276972ec..c427787f78d1 100644
--- a/arch/arm/mach-keystone/platsmp.c
+++ b/arch/arm/mach-keystone/platsmp.c
@@ -26,7 +26,7 @@
 static int keystone_smp_boot_secondary(unsigned int cpu,
 						struct task_struct *idle)
 {
-	unsigned long start = virt_to_idmap(&secondary_startup);
+	unsigned long start = virt_to_idmap(&keystone_secondary_startup);
 	int error;
 
 	pr_debug("keystone-smp: booting cpu %d, vector %08lx\n",
diff --git a/arch/arm/mach-keystone/smc.S b/arch/arm/mach-keystone/smc.S
index d15de8179fab..3ce858ce426e 100644
--- a/arch/arm/mach-keystone/smc.S
+++ b/arch/arm/mach-keystone/smc.S
@@ -23,6 +23,13 @@
  */
 ENTRY(keystone_cpu_smc)
 	stmfd   sp!, {r4-r11, lr}
+ARM_BE8(setend	le)			@ call SMC as LE
 	smc	#0
+ARM_BE8(setend	be)			@ go back to BE8
 	ldmfd   sp!, {r4-r11, pc}
 ENDPROC(keystone_cpu_smc)
+
+ENTRY(keystone_secondary_startup)
+ARM_BE8(setend	be)			@ go BE8 if entered LE
+	b	secondary_startup
+ENDPROC(keyston_secondary_startup)

It would be nice to give this a go once the network driver problem
is solved.

	Arnd