The default dma_ops for devices on arm64 systems are noncoherent in
nature and rely upon special operations and bounce buffers to
perform a device DMA operation to/from memory. Some drivers rely
upon coherent operations involving suitably capable hardware. In
this case, a "dma-coherent" property will exist on the corresponding
Device Tree node for the bridge device, or one of its ancestors.
This patch adds support for applying a DMA coherent dma_ops for
PCI devices in the case of such a property.
Signed-off-by: Jon Masters <j...@redhat.com>
[added search for device with of_node]
Signed-off-by: Mark Salter <msal...@redhat.com>
---
arch/arm64/mm/dma-mapping.c | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 4164c5a..0e26bd7 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -23,10 +23,12 @@
#include <linux/dma-mapping.h>
#include <linux/dma-contiguous.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/vmalloc.h>
#include <linux/swiotlb.h>
#include <linux/amba/bus.h>
+#include <linux/pci.h>
#include <asm/cacheflush.h>
@@ -316,8 +318,18 @@ static int dma_bus_notifier(struct notifier_block *nb,
if (event != BUS_NOTIFY_ADD_DEVICE)
return NOTIFY_DONE;
- if (of_property_read_bool(dev->of_node, "dma-coherent"))
- set_dma_ops(dev, &coherent_swiotlb_dma_ops);
+ /*
+ * Some devices won't have an of_node but a bus controller/bridge will.
+ * Search up the device chain until we find an of_node to check.
+ */
+ while (dev) {
+ if (dev->of_node) {
+ if (of_dma_is_coherent(dev->of_node))
+ set_dma_ops(_dev, &coherent_swiotlb_dma_ops);
+ break;
+ }
+ dev = dev->parent;
+ }
return NOTIFY_OK;
}
@@ -330,6 +342,10 @@ static struct notifier_block amba_bus_nb = {
.notifier_call = dma_bus_notifier,
};
+static struct notifier_block pci_bus_nb = {
+ .notifier_call = dma_bus_notifier,
+};
+
extern int swiotlb_late_init_with_default_size(size_t default_size);
static int __init swiotlb_late_init(void)
@@ -341,6 +357,7 @@ static int __init swiotlb_late_init(void)
*/
bus_register_notifier(&platform_bus_type, &platform_bus_nb);
bus_register_notifier(&amba_bustype, &amba_bus_nb);
+ bus_register_notifier(&pci_bus_type, &pci_bus_nb);
dma_ops = &noncoherent_swiotlb_dma_ops;
--
1.9.3
--
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