firewire: core: optimize propagation of BROADCAST_CHANNEL

Cache the test result of whether a device implements BROADCAST_CHANNEL.
This minimizes traffic on the bus after each bus reset.  A majority of
devices does not implement BROADCAST_CHANNEL.

Remove busy retries; just rely on the hardware to retry requests to busy
responders.  Remove unnecessary log messages.

Rename the flag is_irm to broadcast_channel_allocated to better reflect
its meaning.  Reset the flag earlier in fw_core_handle_bus_reset.

Pass the generation down as a call parameter; that way generation can't
be newer than card->broadcast_channel_allocated and device->node_id.

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

1 files changed, 41 insertions, 4 deletions

diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index a40444e8eb20..a47e2129d83d 100644
--- a/drivers/firewire/fw-device.c
+++ b/drivers/firewire/fw-device.c
@@ -518,7 +518,7 @@ static int read_bus_info_block(struct fw_device *device, int generation)
 
         kfree(old_rom);
         ret = 0;
-        device->cmc = rom[2] & 1 << 30;
+        device->cmc = rom[2] >> 30 & 1;
  out:
         kfree(rom);
 
@@ -756,6 +756,44 @@ static int lookup_existing_device(struct device *dev, void *data)
         return match;
 }
 
+enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
+
+void fw_device_set_broadcast_channel(struct fw_device *device, int generation)
+{
+        struct fw_card *card = device->card;
+        __be32 data;
+        int rcode;
+
+        if (!card->broadcast_channel_allocated)
+                return;
+
+        if (device->bc_implemented == BC_UNKNOWN) {
+                rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
+                                device->node_id, generation, device->max_speed,
+                                CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
+                                &data, 4);
+                switch (rcode) {
+                case RCODE_COMPLETE:
+                        if (data & cpu_to_be32(1 << 31)) {
+                                device->bc_implemented = BC_IMPLEMENTED;
+                                break;
+                        }
+                        /* else fall through to case address error */
+                case RCODE_ADDRESS_ERROR:
+                        device->bc_implemented = BC_UNIMPLEMENTED;
+                }
+        }
+
+        if (device->bc_implemented == BC_IMPLEMENTED) {
+                data = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
+                                   BROADCAST_CHANNEL_VALID);
+                fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
+                                device->node_id, generation, device->max_speed,
+                                CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
+                                &data, 4);
+        }
+}
+
 static void fw_device_init(struct work_struct *work)
 {
         struct fw_device *device =
@@ -849,9 +887,8 @@ static void fw_device_init(struct work_struct *work)
                                   device->config_rom[3], device->config_rom[4],
                                   1 << device->max_speed);
                 device->config_rom_retries = 0;
-                if (device->card->is_irm)
-                        fw_irm_set_broadcast_channel_register(&device->device,
-                                                              NULL);
+
+                fw_device_set_broadcast_channel(device, device->generation);
         }
 
         /*