Add a synchronize helper function for the virt-dma library. The function
makes sure that any scheduled descriptor complete callbacks have finished
running before the function returns.
This needs to be called by drivers using virt-dma in their
device_synchronize() callback. Depending on the driver additional
operations might be necessary in addition to calling vchan_synchronize() to
ensure proper synchronization.
Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
---
drivers/dma/virt-dma.h | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
index 181b9526..e93de76 100644
--- a/drivers/dma/virt-dma.h
+++ b/drivers/dma/virt-dma.h
@@ -151,4 +151,17 @@ static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
vchan_dma_desc_free_list(vc, &head);
}
+/**
+ * vchan_synchronize() - synchronize callback execution to the current context
+ * @vc: virtual channel to synchronize
+ *
+ * Makes sure that all scheduled or active callbacks have finished running. For
+ * proper operation the caller has to ensure that no new callbacks are scheduled
+ * after the invocation of this function started.
+ */
+static inline void vchan_synchronize(struct virt_dma_chan *vc)
+{
+ tasklet_kill(&vc->task);
+}
+
#endif
--
2.1.4
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