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 done in this
patch, thanks to the new bits of infrastructure added in 'ARM: mm:
allow sub-architectures to override PCI I/O memory type' and 'ARM: mm:
add support for HW coherent systems in PL310' respectively.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
---
arch/arm/mach-mvebu/board-v7.c | 51 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c
index 01cfce6..5016c58 100644
--- a/arch/arm/mach-mvebu/board-v7.c
+++ b/arch/arm/mach-mvebu/board-v7.c
@@ -71,6 +71,49 @@ static int armada_375_external_abort_wa(unsigned long addr, unsigned int fsr,
return 1;
}
+/*
+ * This ioremap hook is used on Armada 375/38x to ensure that PCIe
+ * memory areas are mapped as MT_MEMORY_RW_SO 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);
+}
+
+/*
+ * When we are I/O coherent and we use the PL310 cache controller, we
+ * add the PL310 property "dma-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.
+ */
+static void __init mvebu_l2x0_pl310_coherent(void)
+{
+ struct device_node *np;
+
+ if (!coherency_available())
+ return;
+
+ for_each_compatible_node(np, NULL, "arm,pl310-cache") {
+ struct property *p;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ p->name = kstrdup("dma-coherent", GFP_KERNEL);
+ of_add_property(np, p);
+ }
+}
+
static void __init mvebu_timer_and_clk_init(void)
{
of_clk_init(NULL);
@@ -78,6 +121,14 @@ static void __init mvebu_timer_and_clk_init(void)
mvebu_scu_enable();
coherency_init();
BUG_ON(mvebu_mbus_dt_init(coherency_available()));
+
+ if (of_machine_is_compatible("marvell,armada375") ||
+ of_machine_is_compatible("marvell,armada38x")) {
+ arch_ioremap_caller = armada_pcie_wa_ioremap_caller;
+ pci_ioremap_set_mem_type(MT_UNCACHED);
+ mvebu_l2x0_pl310_coherent();
+ }
+
l2x0_of_init(0, ~0UL);
if (of_machine_is_compatible("marvell,armada375"))
--
1.9.3
--
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