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-rw-r--r--drivers/firewire/core-device.c18
1 files changed, 17 insertions, 1 deletions
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index d6e54a5..97e656a 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -580,7 +580,9 @@ static int read_bus_info_block(struct fw_device *device, int generation)
kfree(old_rom);
ret = 0;
- device->cmc = rom[2] >> 30 & 1;
+ device->max_rec = rom[2] >> 12 & 0xf;
+ device->cmc = rom[2] >> 30 & 1;
+ device->irmc = rom[2] >> 31 & 1;
out:
kfree(rom);
@@ -841,6 +843,20 @@ static void set_broadcast_channel(struct fw_device *device, int generation)
if (!card->broadcast_channel_allocated)
return;
+ /*
+ * The Broadcast_Channel Valid bit is required by nodes which want to
+ * transmit on this channel. Such transmissions are practically
+ * exclusive to IP over 1394 (RFC 2734). IP capable nodes are required
+ * to be IRM capable and have a max_rec of 8 or more. We use this fact
+ * to narrow down to which nodes we send Broadcast_Channel updates.
+ */
+ if (!device->irmc || device->max_rec < 8)
+ return;
+
+ /*
+ * Some 1394-1995 nodes crash if this 1394a-2000 register is written.
+ * Perform a read test first.
+ */
if (device->bc_implemented == BC_UNKNOWN) {
rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
device->node_id, generation, device->max_speed,
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