firewire: ohci: 0 may be a valid DMA address

I was told that there are obscure architectures with non-coherent DMA
which may DMA-map to bus address 0.  We shall not use 0 as a magic
number of uninitialized bus address variables.

The packet->payload_length > 0 test cannot be used either (except in
at_context_queue_packet) because local requests are not DMA-mapped
regardless of payload_length.  Hence add a state flag to struct
fw_packet.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index 211a5d7d87b3..9416a461b696 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -267,6 +267,7 @@ struct fw_packet {
         void *payload;
         size_t payload_length;
         dma_addr_t payload_bus;
+        bool payload_mapped;
         u32 timestamp;
 
         /*