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>
diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 4184155..a714775 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -995,7 +995,8 @@
packet->ack = RCODE_SEND_ERROR;
return -1;
}
- packet->payload_bus = payload_bus;
+ packet->payload_bus = payload_bus;
+ packet->payload_mapped = true;
d[2].req_count = cpu_to_le16(packet->payload_length);
d[2].data_address = cpu_to_le32(payload_bus);
@@ -1023,7 +1024,7 @@
*/
if (ohci->generation != packet->generation ||
reg_read(ohci, OHCI1394_IntEventSet) & OHCI1394_busReset) {
- if (packet->payload_length > 0)
+ if (packet->payload_mapped)
dma_unmap_single(ohci->card.device, payload_bus,
packet->payload_length, DMA_TO_DEVICE);
packet->ack = RCODE_GENERATION;
@@ -1059,7 +1060,7 @@
/* This packet was cancelled, just continue. */
return 1;
- if (packet->payload_bus)
+ if (packet->payload_mapped)
dma_unmap_single(ohci->card.device, packet->payload_bus,
packet->payload_length, DMA_TO_DEVICE);
@@ -1723,7 +1724,7 @@
if (packet->ack != 0)
goto out;
- if (packet->payload_bus)
+ if (packet->payload_mapped)
dma_unmap_single(ohci->card.device, packet->payload_bus,
packet->payload_length, DMA_TO_DEVICE);
