firewire: core: don't update Broadcast_Channel if RFC 2734 conditions aren't met

This extra check will avoid Broadcast_Channel register related traffic
to many IIDC, SBP-2, and AV/C devices which aren't IRMC or have a
max_rec < 8 (i.e. support < 512 bytes async payload).  This avoids a
little bit of traffic after bus reset and is even more careful with
devices which don't implement this CSR.

The assumption is that no other protocol than IP over 1394 uses the
broadcast channel for streams.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/firewire.h b/include/linux/firewire.h
index a69aea0394e3..610eade8abb4 100644
--- a/include/linux/firewire.h
+++ b/include/linux/firewire.h
@@ -191,7 +191,9 @@ struct fw_device {
         size_t config_rom_length;
         int config_rom_retries;
         unsigned is_local:1;
+        unsigned max_rec:4;
         unsigned cmc:1;
+        unsigned irmc:1;
         unsigned bc_implemented:2;
 
         struct delayed_work work;