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SubjectRe: [PATCH] ARM: mvebu: Enable MBUS error propagation
On Wednesday 08 January 2020 19:42:12 Chris Packham wrote:
> Hi Gregory,
>
> On Wed, 2020-01-08 at 11:22 +0100, Gregory CLEMENT wrote:
> > Hello Chris,
> >
> > > U-boot disables MBUS error propagation for Armada-385. The effect of
> > > this on the kernel is that any access to a mapped but inaccessible
> > > address causes the system to hang.
> > >
> > > By enabling MBUS error propagation the kernel can raise a Bus Error and
> > > panic to restart the system.
> >
> > Unless I miss it, it seems that nobody comment this patch: sorry for the
> > delay.
> >
>
> Thanks for the response.
>
> > >
> > > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> > > ---
> > >
> > > Notes:
> > > We've encountered an issue where rogue accesses to PCI-e space cause an
> > > Armada-385 system to lockup. We've found that enabling MBUS error
> > > propagation lets us get a bus error which at least gives us a panic to
> > > help identify what was accessed.
> > >
> > > U-boot clears the IO Err Prop Enable Bit[1] but so far no-one seems to
> > > know why.
> > >
> > > I wasn't sure where to put this code. There is similar code for kirwood
> > > in the equivalent dt_init function. On Armada-XP the register is part of
> > > the Core Coherency Fabric block (for A385 it's documented as part of the
> > > CCF block).
> >
> > What about adding a new set of register to the mvebu mbus driver?
> >
>
> After more testing we found that some previously "good" boards started
> throwing up panics with this change. I think that this might require
> handling some of the PCI-e interrupts (for correctable errors) via the
> EDAC subsystem.
>
> We're still working with Marvell to track down exactly why this is
> happening on our system.

Hello Chris! Have you somehow solved this issue? Or do you have some
contacts in Marvell for A385 PCIe subsystem?

> > In this case it will be called even earlier allowing to see bus error
> > earlier.
> >
> > In any case, you should separate the device tree change from the code
> > change and at least provide 2 patches.
>
> Agreed. If/when something solid eventuates we'll do it as a proper
> series.
>
> >
> > Gregory
> >
> > >
> > > --
> > > [1] - https://gitlab.denx.de/u-boot/u-boot/blob/master/arch/arm/mach-mvebu/cpu.c#L489
> > >
> > > arch/arm/boot/dts/armada-38x.dtsi | 5 +++++
> > > arch/arm/mach-mvebu/board-v7.c | 27 +++++++++++++++++++++++++++
> > > 2 files changed, 32 insertions(+)
> > >
> > > diff --git a/arch/arm/boot/dts/armada-38x.dtsi b/arch/arm/boot/dts/armada-38x.dtsi
> > > index 3f4bb44d85f0..3214c67433eb 100644
> > > --- a/arch/arm/boot/dts/armada-38x.dtsi
> > > +++ b/arch/arm/boot/dts/armada-38x.dtsi
> > > @@ -386,6 +386,11 @@
> > > <0x20250 0x8>;
> > > };
> > >
> > > + ioerrc: io-err-control@20200 {
> > > + compatible = "marvell,io-err-control";
> > > + reg = <0x20200 0x4>;
> > > + };
> > > +
> > > mpic: interrupt-controller@20a00 {
> > > compatible = "marvell,mpic";
> > > reg = <0x20a00 0x2d0>, <0x21070 0x58>;
> > > diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c
> > > index d2df5ef9382b..fb7718386ef9 100644
> > > --- a/arch/arm/mach-mvebu/board-v7.c
> > > +++ b/arch/arm/mach-mvebu/board-v7.c
> > > @@ -138,10 +138,36 @@ static void __init i2c_quirk(void)
> > > }
> > > }
> > >
> > > +#define MBUS_ERR_PROP_EN BIT(8)
> > > +
> > > +/*
> > > + * U-boot disables MBUS error propagation. Re-enable it so we
> > > + * can handle them as Bus Errors.
> > > + */
> > > +static void __init enable_mbus_error_propagation(void)
> > > +{
> > > + struct device_node *np =
> > > + of_find_compatible_node(NULL, NULL, "marvell,io-err-control");
> > > +
> > > + if (np) {
> > > + void __iomem *reg;
> > > +
> > > + reg = of_iomap(np, 0);
> > > + if (reg) {
> > > + u32 val;
> > > +
> > > + val = readl_relaxed(reg);
> > > + writel_relaxed(val | MBUS_ERR_PROP_EN, reg);
> > > + }
> > > + of_node_put(np);
> > > + }
> > > +}
> > > +
> > > static void __init mvebu_dt_init(void)
> > > {
> > > if (of_machine_is_compatible("marvell,armadaxp"))
> > > i2c_quirk();
> > > + enable_mbus_error_propagation();
> > > }
> > >
> > > static void __init armada_370_xp_dt_fixup(void)
> > > @@ -191,6 +217,7 @@ DT_MACHINE_START(ARMADA_38X_DT, "Marvell Armada 380/385 (Device Tree)")
> > > .l2c_aux_val = 0,
> > > .l2c_aux_mask = ~0,
> > > .init_irq = mvebu_init_irq,
> > > + .init_machine = mvebu_dt_init,
> > > .restart = mvebu_restart,
> > > .dt_compat = armada_38x_dt_compat,
> > > MACHINE_END
> > > --
> > > 2.24.0
> > >
> >
> >

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