Date: Wed, 19 Dec 2007 03:09:18 -0500 From: David Moore Subject: firewire: fw-ohci: Fix for dualbuffer three-or-more buffers This patch fixes the problem where different OHCI 1.1 controllers behave differently when a received iso packet straddles three or more buffers when using the dual-buffer receive mode. Two changes are made in order to handle this situation: 1. The packet sync DMA descriptor is given a non-zero header length and non-zero payload length. This is because zero-payload descriptors are not discussed in the OHCI 1.1 specs and their behavior is thus undefined. Instead we use a header size just large enough for a single header and a payload length of 4 bytes for this first descriptor. 2. As we process received packets in the context's tasklet, read the packet length out of the headers. Keep track of the running total of the packet length as "excess_bytes", so we can ignore any descriptors where no packet starts or ends. These descriptors may not have had their first_res_count or second_res_count fields updated by the controller so we cannot rely on those values. The main drawback of this patch is that the excess_bytes value might get "out of sync" with the packet descriptors if something strange happens to the DMA program. I'm not if such a thing could ever happen, but I appreciate any suggestions in making it more robust. Also, the packet-per-buffer support may need a similar fix to deal with issue 1, but I haven't done any work on that yet. Stefan, I'm hoping that with this patch, all your OHCI 1.1 controllers will work properly with an unmodified version of libdc1394. Signed-off-by: David Moore --- drivers/firewire/fw-ohci.c | 44 ++++++++++++++++++++++++-------------------- 1 files changed, 24 insertions(+), 20 deletions(-) diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c index 378b1ca..de604f3 100644 --- a/drivers/firewire/fw-ohci.c +++ b/drivers/firewire/fw-ohci.c @@ -146,6 +146,7 @@ struct context { struct iso_context { struct fw_iso_context base; struct context context; + int excess_bytes; void *header; size_t header_length; }; @@ -1472,9 +1473,13 @@ static int handle_ir_dualbuffer_packet(struct context *context, void *p, *end; int i; - if (db->first_res_count > 0 && db->second_res_count > 0) - /* This descriptor isn't done yet, stop iteration. */ - return 0; + if (db->first_res_count > 0 && db->second_res_count > 0) { + if (ctx->excess_bytes <= le16_to_cpu(db->second_req_count)) { + /* This descriptor isn't done yet, stop iteration. */ + return 0; + } + ctx->excess_bytes -= le16_to_cpu(db->second_req_count); + } header_length = le16_to_cpu(db->first_req_count) - le16_to_cpu(db->first_res_count); @@ -1493,11 +1498,15 @@ static int handle_ir_dualbuffer_packet(struct context *context, *(u32 *) (ctx->header + i) = __swab32(*(u32 *) (p + 4)); memcpy(ctx->header + i + 4, p + 8, ctx->base.header_size - 4); i += ctx->base.header_size; + ctx->excess_bytes += + (le32_to_cpu(*(u32 *)(p + 4)) >> 16) & 0xffff; p += ctx->base.header_size + 4; } - ctx->header_length = i; + ctx->excess_bytes -= le16_to_cpu(db->second_req_count) - + le16_to_cpu(db->second_res_count); + if (le16_to_cpu(db->control) & DESCRIPTOR_IRQ_ALWAYS) { ir_header = (__le32 *) (db + 1); ctx->base.callback(&ctx->base, @@ -1838,19 +1847,6 @@ ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base, * packet, retransmit or terminate.. */ - if (packet->skip) { - d = context_get_descriptors(&ctx->context, 2, &d_bus); - if (d == NULL) - return -ENOMEM; - - db = (struct db_descriptor *) d; - db->control = cpu_to_le16(DESCRIPTOR_STATUS | - DESCRIPTOR_BRANCH_ALWAYS | - DESCRIPTOR_WAIT); - db->first_size = cpu_to_le16(ctx->base.header_size + 4); - context_append(&ctx->context, d, 2, 0); - } - p = packet; z = 2; @@ -1878,11 +1874,18 @@ ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base, db->control = cpu_to_le16(DESCRIPTOR_STATUS | DESCRIPTOR_BRANCH_ALWAYS); db->first_size = cpu_to_le16(ctx->base.header_size + 4); - db->first_req_count = cpu_to_le16(header_size); + if (p->skip && rest == p->payload_length) { + db->control |= cpu_to_le16(DESCRIPTOR_WAIT); + db->first_req_count = db->first_size; + } else { + db->first_req_count = cpu_to_le16(header_size); + } db->first_res_count = db->first_req_count; db->first_buffer = cpu_to_le32(d_bus + sizeof(*db)); - if (offset + rest < PAGE_SIZE) + if (p->skip && rest == p->payload_length) + length = 4; + else if (offset + rest < PAGE_SIZE) length = rest; else length = PAGE_SIZE - offset; @@ -1898,7 +1901,8 @@ ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base, context_append(&ctx->context, d, z, header_z); offset = (offset + length) & ~PAGE_MASK; rest -= length; - page++; + if (offset == 0) + page++; } return 0;