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path: root/drivers/acpi/scan.c
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Diffstat (limited to 'drivers/acpi/scan.c')
-rw-r--r--drivers/acpi/scan.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index 4bbc8f89257f..2649a068671d 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -11,6 +11,7 @@
#include <linux/kthread.h>
#include <linux/dmi.h>
#include <linux/nls.h>
+#include <linux/dma-mapping.h>
#include <asm/pgtable.h>
@@ -2153,6 +2154,39 @@ void acpi_free_pnp_ids(struct acpi_device_pnp *pnp)
kfree(pnp->unique_id);
}
+static void acpi_init_coherency(struct acpi_device *adev)
+{
+ unsigned long long cca = 0;
+ acpi_status status;
+ struct acpi_device *parent = adev->parent;
+
+ if (parent && parent->flags.cca_seen) {
+ /*
+ * From ACPI spec, OSPM will ignore _CCA if an ancestor
+ * already saw one.
+ */
+ adev->flags.cca_seen = 1;
+ cca = parent->flags.coherent_dma;
+ } else {
+ status = acpi_evaluate_integer(adev->handle, "_CCA",
+ NULL, &cca);
+ if (ACPI_SUCCESS(status))
+ adev->flags.cca_seen = 1;
+ else if (!IS_ENABLED(CONFIG_ACPI_CCA_REQUIRED))
+ /*
+ * If architecture does not specify that _CCA is
+ * required for DMA-able devices (e.g. x86),
+ * we default to _CCA=1.
+ */
+ cca = 1;
+ else
+ acpi_handle_debug(adev->handle,
+ "ACPI device is missing _CCA.\n");
+ }
+
+ adev->flags.coherent_dma = cca;
+}
+
void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
int type, unsigned long long sta)
{
@@ -2171,6 +2205,7 @@ void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
device->flags.visited = false;
device_initialize(&device->dev);
dev_set_uevent_suppress(&device->dev, true);
+ acpi_init_coherency(device);
}
void acpi_device_add_finalize(struct acpi_device *device)