[PATCH] [ARM] Kirkwood: Prevent kernel from crashing if PCIe bridge is present

[dk-arm-linux@gmx.de (Dieter Kiermaier)]

Hi Lennert,

> On Thu, Nov 12, 2009 at 06:19:42AM -0800, Dieter Kiermaier wrote:
> 
> > Below you can find a first version of the patch which enables PCI on my openrd-base board
> > together with a PCIe->PCI bridge.
> > Please let me know if something is wrong with it.
> >
> > [...]
> > 
> > Subject: [PATCH] [ARM] Kirkwood: Prevent kernel from crashing if PCIe bridge is present
> 
> In the end, this is what the patch does, but the issue it solves is (at
> least in theory) not specific to PCI.
> 
> 
> > If this bit isn't disabled kernel crash during bootup when booted
> > with current mainline u-boot (version U-Boot 2009.08-00208-g9ef0569)
> > and a PCIe -> PCI bridge is connected to the system.
> 
> And this should really explain why the crash happens (which is because
> there is a PCI master abort because the PCI scanning code probes all
> possible device IDs on the secondary side of the bridge).

thanks for being patient and explain it that even a newbie can understand what's going on here!

> 
> 
> > diff --git a/arch/arm/mach-kirkwood/openrd_base-setup.c b/arch/arm/mach-kirkwood/openrd_base-setup.c
> > index 77617c7..9e57326 100644
> > --- a/arch/arm/mach-kirkwood/openrd_base-setup.c
> > +++ b/arch/arm/mach-kirkwood/openrd_base-setup.c
> 
> This issue is not OpenRD-specific, so shouldn't be handled in the
> OpenRD board setup file.
> 
> 
> >  static int __init openrd_base_pci_init(void)
> >  {
> > +	u32 cpu_config_reg;
> > +	void __iomem *base;
> > +	base = ioremap(0xf1020100, 4);
> > +	if (base)
> > +	{
> > +		cpu_config_reg = readl(base);
> > +		cpu_config_reg &= ~(1 << 2);
> > +		writel(cpu_config_reg, base);
> > +	}
> > +	iounmap(base);
> 
> There's no need to ioremap/iounmap -- the 1MB block of CPU peripheral
> registers is permanently mapped into the kernel virtual address
> region.
> 
> How about something like this instead?  (Since you did most of the work
> I don't mind having you as the From: on the patch.)
> 
Your version looks much more comprehensible so I would prefer your's.
And I've no problem with not being mentioned "from:" because most of the
work is done by Maxime, Alexander and yourself!

I've only triggered it - so reported by fits fine!

Will this patch together with Maximes patch:
http://lists.infradead.org/pipermail/linux-arm-kernel/2009-November/003784.html
applied to marvell orion.git and also upstream?

Dieter
> 
> 
> commit 728ae3400ef8fc3da10491d48e6832b6bb7aa281
> Author: Lennert Buytenhek <buytenh@wantstofly.org>
> Date:   Thu Nov 12 20:31:14 2009 +0100
> 
>     [ARM] Kirkwood: disable propagation of mbus error to the CPU local bus
>     
>     Disable propagation of mbus errors to the CPU local bus, as this causes
>     mbus errors (which can occur for example for PCI aborts) to throw CPU
>     aborts, which we're not set up to deal with.
>     
>     Reported-by: Dieter Kiermaier <dk-arm-linux@gmx.de>
>     Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
> 
> diff --git a/arch/arm/mach-kirkwood/common.c b/arch/arm/mach-kirkwood/common.c
> index 0acb61f..96c98c2 100644
> --- a/arch/arm/mach-kirkwood/common.c
> +++ b/arch/arm/mach-kirkwood/common.c
> @@ -915,6 +915,14 @@ void __init kirkwood_init(void)
>  	kirkwood_uart0_data[0].uartclk = kirkwood_tclk;
>  	kirkwood_uart1_data[0].uartclk = kirkwood_tclk;
>  
> +	/*
> +	 * Disable propagation of mbus errors to the CPU local bus,
> +	 * as this causes mbus errors (which can occur for example
> +	 * for PCI aborts) to throw CPU aborts, which we're not set
> +	 * up to deal with.
> +	 */
> +	writel(readl(CPU_CONFIG) & ~CPU_CONFIG_ERROR_PROP, CPU_CONFIG);
> +
>  	kirkwood_setup_cpu_mbus();
>  
>  #ifdef CONFIG_CACHE_FEROCEON_L2
> diff --git a/arch/arm/mach-kirkwood/include/mach/bridge-regs.h b/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
> index 9e80d92..418f501 100644
> --- a/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
> +++ b/arch/arm/mach-kirkwood/include/mach/bridge-regs.h
> @@ -13,6 +13,9 @@
>  
>  #include <mach/kirkwood.h>
>  
> +#define CPU_CONFIG		(BRIDGE_VIRT_BASE | 0x0100)
> +#define CPU_CONFIG_ERROR_PROP	0x00000004
> +
>  #define CPU_CONTROL		(BRIDGE_VIRT_BASE | 0x0104)
>  #define CPU_RESET		0x00000002
>  
> --
> 
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