arm: kirkwood: register DT devices earlier

The board-dt.c initialization functions calls the per-board legacy init functions (to probe devices that have not yet been converted to the Device Tree) before probing the devices declared in the Device Tree.

This unfortunately causes a boot crash on Topkick, because the board-specific initialization function sets a GPIO to some value. Unfortunately, since the devices declared in the Device Tree haven't been probed, the GPIO controllers haven't been probed, and the gpio_set_value() call causes the following crash:

Unable to handle kernel NULL pointer dereference at virtual address 00000040
pgd = c0004000
[00000040] *pgd=00000000
Internal error: Oops: 5 [#1] PREEMPT ARM
Modules linked in:
CPU: 0    Not tainted  (3.7.0-rc7-01461-g2ef9d7a-dirty #91)
PC is at __gpio_set_value+0x20/0xb4
LR is at usi_topkick_init+0x18/0x2c

Therefore, we invert the order of initialization: we first probe Device Tree devices, and then allow per-board initialization functions to do add more devices if they wish.

---
 arch/arm/mach-kirkwood/board-dt.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

index ff4150a..d8a0275 100644
@@ -97,6 +97,7 @@ static void __init kirkwood_dt_init(void)
 #ifdef CONFIG_KEXEC
 	kexec_reinit = kirkwood_enable_pcie;
 #endif
+	of_platform_populate(NULL, kirkwood_dt_match_table, NULL, NULL);
 
 	if (of_machine_is_compatible("globalscale,dreamplug"))
 		dreamplug_init();

@@ -146,8 +147,6 @@ static void __init kirkwood_dt_init(void)
 
 	if (of_machine_is_compatible("zyxel,nsa310"))
 		nsa310_init();
-
-	of_platform_populate(NULL, kirkwood_dt_match_table, NULL, NULL);
 }
 
 static const char * const kirkwood_dt_board_compat[] = {

1.7.9.5

Hi Thomas

I have a different fix for this.

The gpio is being used to supply power to SATA. So i turn it into a fixed-regulator, using DT.

I will send the patch tonight.

Andrew

Dear Andrew Lunn,

Indeed sounds a much better fix than mine. My patch posting was mainly to raise the issue, and ensure we get some fix for it, I was quite sure there was a better way of fixing this.

Thanks,

Thomas

Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com