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Subject[PATCH 2/2] 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.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
---
drivers/firewire/core-transaction.c | 4 ++--
drivers/firewire/ohci.c | 9 +++++----
include/linux/firewire.h | 1 +
3 files changed, 8 insertions(+), 6 deletions(-)

Index: linux-2.6.31/drivers/firewire/ohci.c
===================================================================
--- linux-2.6.31.orig/drivers/firewire/ohci.c
+++ linux-2.6.31/drivers/firewire/ohci.c
@@ -995,7 +995,8 @@ static int at_context_queue_packet(struc
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 @@ static int at_context_queue_packet(struc
*/
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 @@ static int handle_at_packet(struct conte
/* 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 @@ static int ohci_cancel_packet(struct fw_
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);

Index: linux-2.6.31/drivers/firewire/core-transaction.c
===================================================================
--- linux-2.6.31.orig/drivers/firewire/core-transaction.c
+++ linux-2.6.31/drivers/firewire/core-transaction.c
@@ -226,7 +226,7 @@ static void fw_fill_request(struct fw_pa
packet->speed = speed;
packet->generation = generation;
packet->ack = 0;
- packet->payload_bus = 0;
+ packet->payload_mapped = false;
}

/**
@@ -601,7 +601,7 @@ void fw_fill_response(struct fw_packet *
WARN(1, KERN_ERR "wrong tcode %d", tcode);
}

- response->payload_bus = 0;
+ response->payload_mapped = false;
}
EXPORT_SYMBOL(fw_fill_response);

Index: linux-2.6.31/include/linux/firewire.h
===================================================================
--- linux-2.6.31.orig/include/linux/firewire.h
+++ linux-2.6.31/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;

/*
--
Stefan Richter
-=====-==--= =-=- -===-
http://arcgraph.de/sr/


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