firewire: ohci: avoid separate DMA mapping for small AT payloads

[karo-tx-linux.git] / drivers / firewire / ohci.c

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index dfb3cb774a790827d374ebc15ce693a92ed3f1f6..435ed800d03ff6c6462a4a2ba44b9cc8a620f079 100644 (file)
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -1218,6 +1218,7 @@ static void context_stop(struct context *ctx)
 }
 
 struct driver_data {
+       u8 inline_data[8];
        struct fw_packet *packet;
 };
 
@@ -1301,20 +1302,28 @@ static int at_context_queue_packet(struct context *ctx,
                return -1;
        }
 
+       BUILD_BUG_ON(sizeof(struct driver_data) > sizeof(struct descriptor));
        driver_data = (struct driver_data *) &d[3];
        driver_data->packet = packet;
        packet->driver_data = driver_data;
 
        if (packet->payload_length > 0) {
-               payload_bus =
-                       dma_map_single(ohci->card.device, packet->payload,
-                                      packet->payload_length, DMA_TO_DEVICE);
-               if (dma_mapping_error(ohci->card.device, payload_bus)) {
-                       packet->ack = RCODE_SEND_ERROR;
-                       return -1;
+               if (packet->payload_length > sizeof(driver_data->inline_data)) {
+                       payload_bus = dma_map_single(ohci->card.device,
+                                                    packet->payload,
+                                                    packet->payload_length,
+                                                    DMA_TO_DEVICE);
+                       if (dma_mapping_error(ohci->card.device, payload_bus)) {
+                               packet->ack = RCODE_SEND_ERROR;
+                               return -1;
+                       }
+                       packet->payload_bus     = payload_bus;
+                       packet->payload_mapped  = true;
+               } else {
+                       memcpy(driver_data->inline_data, packet->payload,
+                              packet->payload_length);
+                       payload_bus = d_bus + 3 * sizeof(*d);
                }
-               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);