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ARM: mvebu: implement L2/PCIe deadlock workaround

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The Marvell Armada 375 and Armada 38x SOCs, which use the Cortex-A9
CPU core, the PL310 cache and the Marvell PCIe hardware block are
affected a L2/PCIe deadlock caused by a system erratum when hardware
I/O coherency is used.

This deadlock can be avoided by mapping the PCIe memory areas as
strongly-ordered (note: MT_UNCACHED is strongly-ordered), and by
removing the outer cache sync done in software. This is implemented in
this patch by:

 * Registering a custom arch_ioremap_caller function that allows to
   make sure PCI memory regions are mapped MT_UNCACHED.

 * Adding at runtime the 'arm,io-coherent' property to the PL310 cache
   controller. This cannot be done permanently in the DT, because the
   hardware I/O coherency can only be enabled when CONFIG_SMP is
   enabled, in the current kernel situation.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1400165974-9059-4-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Thomas Petazzoni 2014-05-15 16:59:34 +02:00 committed by Jason Cooper
parent b0063aad5d
commit 497a92308a
1 changed files with 39 additions and 0 deletions
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39
arch/arm/mach-mvebu/coherency.c
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@ -32,6 +32,7 @@
#include <linux/pci.h>
#include <asm/smp_plat.h>
#include <asm/cacheflush.h>
#include <asm/mach/map.h>
#include "armada-370-xp.h"
#include "coherency.h"
#include "mvebu-soc-id.h"
@ -309,9 +310,47 @@ static void __init armada_370_coherency_init(struct device_node *np)
set_cpu_coherent();
}
/*
* This ioremap hook is used on Armada 375/38x to ensure that PCIe
* memory areas are mapped as MT_UNCACHED instead of MT_DEVICE. This
* is needed as a workaround for a deadlock issue between the PCIe
* interface and the cache controller.
*/
static void __iomem *
armada_pcie_wa_ioremap_caller(phys_addr_t phys_addr, size_t size,
unsigned int mtype, void *caller)
{
struct resource pcie_mem;
mvebu_mbus_get_pcie_mem_aperture(&pcie_mem);
if (pcie_mem.start <= phys_addr && (phys_addr + size) <= pcie_mem.end)
mtype = MT_UNCACHED;
return __arm_ioremap_caller(phys_addr, size, mtype, caller);
}
static void __init armada_375_380_coherency_init(struct device_node *np)
{
struct device_node *cache_dn;
coherency_cpu_base = of_iomap(np, 0);
arch_ioremap_caller = armada_pcie_wa_ioremap_caller;
/*
* Add the PL310 property "arm,io-coherent". This makes sure the
* outer sync operation is not used, which allows to
* workaround the system erratum that causes deadlocks when
* doing PCIe in an SMP situation on Armada 375 and Armada
* 38x.
*/
for_each_compatible_node(cache_dn, NULL, "arm,pl310-cache") {
struct property *p;
p = kzalloc(sizeof(*p), GFP_KERNEL);
p->name = kstrdup("arm,io-coherent", GFP_KERNEL);
of_add_property(cache_dn, p);
}
}
static int coherency_type(void)