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>

diff --git a/drivers/firewire/fw-card.c b/drivers/firewire/fw-card.c
index d63d0ed..8b8c8c2 100644 (file)
--- a/drivers/firewire/fw-card.c
+++ b/drivers/firewire/fw-card.c
@@ -181,83 +181,9 @@ void fw_core_remove_descriptor(struct fw_descriptor *desc)
        mutex_unlock(&card_mutex);
 }
 
-#define IRM_RETRIES 2
-
-/*
- * The abi is set by device_for_each_child(), even though we have no use
- * for data, nor do we have a meaningful return value.
- */
-int fw_irm_set_broadcast_channel_register(struct device *dev, void *data)
+static int set_broadcast_channel(struct device *dev, void *data)
 {
-       struct fw_device *d;
-       int rcode;
-       int node_id;
-       int max_speed;
-       int retries;
-       int generation;
-       __be32 regval;
-       struct fw_card *card;
-
-       d = fw_device(dev);
-       /* FIXME: do we need locking here? */
-       generation = d->generation;
-       smp_rmb(); /* Ensure generation is at least as old as node_id */
-       node_id = d->node_id;
-       max_speed = d->max_speed;
-       retries = IRM_RETRIES;
-       card = d->card;
-tryagain_r:
-       rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
-                                  node_id, generation, max_speed,
-                                  CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
-                                  &regval, 4);
-       switch (rcode) {
-       case RCODE_BUSY:
-               if (retries--)
-                       goto tryagain_r;
-               fw_notify("node %x read broadcast channel busy\n",
-                         node_id);
-               return 0;
-
-       default:
-               fw_notify("node %x read broadcast channel failed %x\n",
-                         node_id, rcode);
-               return 0;
-
-       case RCODE_COMPLETE:
-               /*
-                * Paranoid reporting of nonstandard broadcast channel
-                * contents goes here
-                */
-               if (regval != cpu_to_be32(BROADCAST_CHANNEL_INITIAL))
-                       return 0;
-               break;
-       }
-       retries = IRM_RETRIES;
-       regval = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
-                            BROADCAST_CHANNEL_VALID);
-tryagain_w:
-       rcode = fw_run_transaction(card,
-                       TCODE_WRITE_QUADLET_REQUEST, node_id,
-                       generation, max_speed,
-                       CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
-                       &regval, 4);
-       switch (rcode) {
-       case RCODE_BUSY:
-               if (retries--)
-                       goto tryagain_w;
-               fw_notify("node %x write broadcast channel busy\n",
-                         node_id);
-               return 0;
-
-       default:
-               fw_notify("node %x write broadcast channel failed %x\n",
-                         node_id, rcode);
-               return 0;
-
-       case RCODE_COMPLETE:
-               return 0;
-       }
+       fw_device_set_broadcast_channel(fw_device(dev), (long)data);
        return 0;
 }
 
@@ -268,9 +194,9 @@ static void allocate_broadcast_channel(struct fw_card *card, int generation)
        fw_iso_resource_manage(card, generation, 1ULL << 31,
                               &channel, &bandwidth, true);
        if (channel == 31) {
-               card->is_irm = true;
-               device_for_each_child(card->device, NULL,
-                                     fw_irm_set_broadcast_channel_register);
+               card->broadcast_channel_allocated = true;
+               device_for_each_child(card->device, (void *)(long)generation,
+                                     set_broadcast_channel);
        }
 }
 
@@ -302,7 +228,6 @@ static void fw_card_bm_work(struct work_struct *work)
        __be32 lock_data[2];
 
        spin_lock_irqsave(&card->lock, flags);
-       card->is_irm = false;
 
        if (card->local_node == NULL) {
                spin_unlock_irqrestore(&card->lock, flags);

diff --git a/drivers/firewire/fw-device.c b/drivers/firewire/fw-device.c
index a40444e..a47e212 100644 (file)
--- 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);
        }
 
        /*

diff --git a/drivers/firewire/fw-device.h b/drivers/firewire/fw-device.h
index 3085a74..9758893 100644 (file)
--- a/drivers/firewire/fw-device.h
+++ b/drivers/firewire/fw-device.h
@@ -71,7 +71,6 @@ struct fw_device {
        int node_id;
        int generation;
        unsigned max_speed;
-       bool cmc;
        struct fw_card *card;
        struct device device;
 
@@ -81,6 +80,9 @@ struct fw_device {
        u32 *config_rom;
        size_t config_rom_length;
        int config_rom_retries;
+       unsigned cmc:1;
+       unsigned bc_implemented:2;
+
        struct delayed_work work;
        struct fw_attribute_group attribute_group;
 };
@@ -109,6 +111,7 @@ static inline void fw_device_put(struct fw_device *device)
 
 struct fw_device *fw_device_get_by_devt(dev_t devt);
 int fw_device_enable_phys_dma(struct fw_device *device);
+void fw_device_set_broadcast_channel(struct fw_device *device, int generation);
 
 void fw_device_cdev_update(struct fw_device *device);
 void fw_device_cdev_remove(struct fw_device *device);

diff --git a/drivers/firewire/fw-topology.c b/drivers/firewire/fw-topology.c
index b44131c..d0deecc 100644 (file)
--- a/drivers/firewire/fw-topology.c
+++ b/drivers/firewire/fw-topology.c
@@ -526,6 +526,7 @@ void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 
        spin_lock_irqsave(&card->lock, flags);
 
+       card->broadcast_channel_allocated = false;
        card->node_id = node_id;
        /*
         * Update node_id before generation to prevent anybody from using

diff --git a/drivers/firewire/fw-transaction.h b/drivers/firewire/fw-transaction.h
index d4f42ce..dfa7990 100644 (file)
--- a/drivers/firewire/fw-transaction.h
+++ b/drivers/firewire/fw-transaction.h
@@ -230,11 +230,6 @@ struct fw_card {
        u8 color; /* must be u8 to match the definition in struct fw_node */
        int gap_count;
        bool beta_repeaters_present;
-       /*
-        * Set if the local device is the IRM and the broadcast channel
-        * was allocated.
-        */
-       bool is_irm;
 
        int index;
 
@@ -245,6 +240,7 @@ struct fw_card {
        int bm_retries;
        int bm_generation;
 
+       bool broadcast_channel_allocated;
        u32 broadcast_channel;
        u32 topology_map[(CSR_TOPOLOGY_MAP_END - CSR_TOPOLOGY_MAP) / 4];
 };