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firewire: OHCI 1.0 Isochronous Receive support
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Third rendition of FireWire OHCI 1.0 Isochronous Receive support, using a
zer-copy method similar to OHCI 1.1 which puts the IR data payload directly
into the userspace buffer. The zero-copy implementation eliminates the
video artifacts, audio popping, and buffer underrun problems seen with
version 1 of this patch, as well as fixing a regression in OHCI 1.1 support
introduced by version 2 of this patch.

Successfully tested in OHCI 1.1 mode on the following chipsets:

- NEC uPD72847 (rev 01), OHCI 1.1 (PCI)
- Ti XIO2200(A) (rev 01), OHCI 1.1 (PCIe)
- Ti TSB41AB2 (rev 01), OHCI 1.1 (PCI on SB Audigy)
- Apple UniNorth 2 (rev 81), OHCI 1.1 (PowerBook G4 onboard)

Successfully tested in OHCI 1.0 mode on the following chipsets:

- Agere FW323 (rev 06), OHCI 1.0 (Mac Mini onboard)
- Agere FW323 (rev 06), OHCI 1.0 (PCI)
- Via VT6306 (rev 46), OHCI 1.0 (PCI)
- NEC OrangeLink (rev 01), OHCI 1.0 (PCI)
- NEC uPD72847 (rev 01), OHCI 1.1 (PCI)
- Ti XIO2200(A) (rev 01), OHCI 1.1 (PCIe)

The bulk of testing was done in an x86_64 system, but was also successfully
sanity-tested on other systems, including a PPC(32) PowerBook G4 and an i686
EPIA M10k. Crude benchmarking (watching top during capture) puts the cpu
utilization during capture on the EPIA's 1GHz Via C3 processor around 13%,
which is down from 30% with the v1 code.

Some implementation details:

To maintain the same userspace API as dual-buffer mode, we set up two
descriptors for every incoming packet. The first is an INPUT_MORE descriptor,
pointing to a buffer large enough to hold just the packet's iso headers,
immediately followed by an INPUT_LAST descriptor, pointing to a chunk of the
userspace buffer big enough for the packet's data payload. With this setup,
each incoming packet fills in these two descriptors in a manner that very
closely emulates dual-buffer receive, to the point where the bulk of the
handle_ir_* code is now identical between the two (and probably primed for
some restructuring to share code between them).

The only caveat I have at the moment is that neither of my OHCI 1.0 Via
VT6307-based FireWire controllers work particularly well with this code
for reasons I have yet to figure out.

Signed-off-by: Jarod Wilson <jwilson@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
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Jarod Wilson authored and Stefan Richter committed Dec 10, 2007
1 parent 41f81e8 commit a186b4a
Showing 1 changed file with 155 additions and 20 deletions.
175 changes: 155 additions & 20 deletions drivers/firewire/fw-ohci.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -437,6 +437,21 @@ static void ar_context_run(struct ar_context *ctx)
flush_writes(ctx->ohci);
}

static struct descriptor *
find_branch_descriptor(struct descriptor *d, int z)
{
int b, key;

b = (le16_to_cpu(d->control) & DESCRIPTOR_BRANCH_ALWAYS) >> 2;
key = (le16_to_cpu(d->control) & DESCRIPTOR_KEY_IMMEDIATE) >> 8;

/* figure out which descriptor the branch address goes in */
if (z == 2 && (b == 3 || key == 2))
return d;
else
return d + z - 1;
}

static void context_tasklet(unsigned long data)
{
struct context *ctx = (struct context *) data;
Expand All @@ -455,7 +470,7 @@ static void context_tasklet(unsigned long data)
address = le32_to_cpu(last->branch_address);
z = address & 0xf;
d = ctx->buffer + (address - ctx->buffer_bus) / sizeof(*d);
last = (z == 2) ? d : d + z - 1;
last = find_branch_descriptor(d, z);

if (!ctx->callback(ctx, d, last))
break;
Expand Down Expand Up @@ -566,7 +581,7 @@ static void context_append(struct context *ctx,

ctx->head_descriptor = d + z + extra;
ctx->prev_descriptor->branch_address = cpu_to_le32(d_bus | z);
ctx->prev_descriptor = z == 2 ? d : d + z - 1;
ctx->prev_descriptor = find_branch_descriptor(d, z);

dma_sync_single_for_device(ctx->ohci->card.device, ctx->buffer_bus,
ctx->buffer_size, DMA_TO_DEVICE);
Expand Down Expand Up @@ -655,7 +670,7 @@ at_context_queue_packet(struct context *ctx, struct fw_packet *packet)
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,
Expand Down Expand Up @@ -903,7 +918,7 @@ at_context_transmit(struct context *ctx, struct fw_packet *packet)

if (retval < 0)
packet->callback(packet, &ctx->ohci->card, packet->ack);

}

static void bus_reset_tasklet(unsigned long data)
Expand Down Expand Up @@ -1431,6 +1446,57 @@ static int handle_ir_dualbuffer_packet(struct context *context,
return 1;
}

static int handle_ir_packet_per_buffer(struct context *context,
struct descriptor *d,
struct descriptor *last)
{
struct iso_context *ctx =
container_of(context, struct iso_context, context);
struct descriptor *pd = d + 1;
__le32 *ir_header;
size_t header_length;
void *p, *end;
int i, z;

if (pd->res_count == pd->req_count)
/* Descriptor(s) not done yet, stop iteration */
return 0;

header_length = le16_to_cpu(d->req_count);

i = ctx->header_length;
z = le32_to_cpu(pd->branch_address) & 0xf;
p = d + z;
end = p + header_length;

while (p < end && i + ctx->base.header_size <= PAGE_SIZE) {
/*
* The iso header is byteswapped to little endian by
* the controller, but the remaining header quadlets
* are big endian. We want to present all the headers
* as big endian, so we have to swap the first quadlet.
*/
*(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;
p += ctx->base.header_size + 4;
}

ctx->header_length = i;

if (le16_to_cpu(pd->control) & DESCRIPTOR_IRQ_ALWAYS) {
ir_header = (__le32 *) (d + z);
ctx->base.callback(&ctx->base,
le32_to_cpu(ir_header[0]) & 0xffff,
ctx->header_length, ctx->header,
ctx->base.callback_data);
ctx->header_length = 0;
}


return 1;
}

static int handle_it_packet(struct context *context,
struct descriptor *d,
struct descriptor *last)
Expand Down Expand Up @@ -1466,14 +1532,12 @@ ohci_allocate_iso_context(struct fw_card *card, int type, size_t header_size)
} else {
mask = &ohci->ir_context_mask;
list = ohci->ir_context_list;
callback = handle_ir_dualbuffer_packet;
if (ohci->version >= OHCI_VERSION_1_1)
callback = handle_ir_dualbuffer_packet;
else
callback = handle_ir_packet_per_buffer;
}

/* FIXME: We need a fallback for pre 1.1 OHCI. */
if (callback == handle_ir_dualbuffer_packet &&
ohci->version < OHCI_VERSION_1_1)
return ERR_PTR(-ENOSYS);

spin_lock_irqsave(&ohci->lock, flags);
index = ffs(*mask) - 1;
if (index >= 0)
Expand Down Expand Up @@ -1532,7 +1596,9 @@ static int ohci_start_iso(struct fw_iso_context *base,
context_run(&ctx->context, match);
} else {
index = ctx - ohci->ir_context_list;
control = IR_CONTEXT_DUAL_BUFFER_MODE | IR_CONTEXT_ISOCH_HEADER;
control = IR_CONTEXT_ISOCH_HEADER;
if (ohci->version >= OHCI_VERSION_1_1)
control |= IR_CONTEXT_DUAL_BUFFER_MODE;
match = (tags << 28) | (sync << 8) | ctx->base.channel;
if (cycle >= 0) {
match |= (cycle & 0x07fff) << 12;
Expand Down Expand Up @@ -1738,7 +1804,6 @@ ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base,
offset = payload & ~PAGE_MASK;
rest = p->payload_length;

/* FIXME: OHCI 1.0 doesn't support dual buffer receive */
/* FIXME: make packet-per-buffer/dual-buffer a context option */
while (rest > 0) {
d = context_get_descriptors(&ctx->context,
Expand Down Expand Up @@ -1776,6 +1841,81 @@ ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base,
return 0;
}

static int
ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
struct fw_iso_packet *packet,
struct fw_iso_buffer *buffer,
unsigned long payload)
{
struct iso_context *ctx = container_of(base, struct iso_context, base);
struct descriptor *d = NULL, *pd = NULL;
struct fw_iso_packet *p;
dma_addr_t d_bus, page_bus;
u32 z, header_z, rest;
int i, page, offset, packet_count, header_size;

if (packet->skip) {
d = context_get_descriptors(&ctx->context, 1, &d_bus);
if (d == NULL)
return -ENOMEM;

d->control = cpu_to_le16(DESCRIPTOR_STATUS |
DESCRIPTOR_INPUT_LAST |
DESCRIPTOR_BRANCH_ALWAYS |
DESCRIPTOR_WAIT);
context_append(&ctx->context, d, 1, 0);
}

/* one descriptor for header, one for payload */
/* FIXME: handle cases where we need multiple desc. for payload */
z = 2;
p = packet;

/*
* The OHCI controller puts the status word in the
* buffer too, so we need 4 extra bytes per packet.
*/
packet_count = p->header_length / ctx->base.header_size;
header_size = packet_count * (ctx->base.header_size + 4);

/* Get header size in number of descriptors. */
header_z = DIV_ROUND_UP(header_size, sizeof(*d));
page = payload >> PAGE_SHIFT;
offset = payload & ~PAGE_MASK;
rest = p->payload_length;

for (i = 0; i < packet_count; i++) {
/* d points to the header descriptor */
d = context_get_descriptors(&ctx->context,
z + header_z, &d_bus);
if (d == NULL)
return -ENOMEM;

d->control = cpu_to_le16(DESCRIPTOR_INPUT_MORE);
d->req_count = cpu_to_le16(header_size);
d->res_count = d->req_count;
d->data_address = cpu_to_le32(d_bus + (z * sizeof(*d)));

/* pd points to the payload descriptor */
pd = d + 1;
pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
DESCRIPTOR_INPUT_LAST |
DESCRIPTOR_BRANCH_ALWAYS);
if (p->interrupt)
pd->control |= cpu_to_le16(DESCRIPTOR_IRQ_ALWAYS);

pd->req_count = cpu_to_le16(rest);
pd->res_count = pd->req_count;

page_bus = page_private(buffer->pages[page]);
pd->data_address = cpu_to_le32(page_bus + offset);

context_append(&ctx->context, d, z, header_z);
}

return 0;
}

static int
ohci_queue_iso(struct fw_iso_context *base,
struct fw_iso_packet *packet,
Expand All @@ -1790,8 +1930,9 @@ ohci_queue_iso(struct fw_iso_context *base,
return ohci_queue_iso_receive_dualbuffer(base, packet,
buffer, payload);
else
/* FIXME: Implement fallback for OHCI 1.0 controllers. */
return -ENOSYS;
return ohci_queue_iso_receive_packet_per_buffer(base, packet,
buffer,
payload);
}

static const struct fw_card_driver ohci_driver = {
Expand Down Expand Up @@ -1911,12 +2052,6 @@ pci_probe(struct pci_dev *dev, const struct pci_device_id *ent)
ohci->version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff;
fw_notify("Added fw-ohci device %s, OHCI version %x.%x\n",
dev->dev.bus_id, ohci->version >> 16, ohci->version & 0xff);
if (ohci->version < OHCI_VERSION_1_1) {
fw_notify(" Isochronous I/O is not yet implemented for "
"OHCI 1.0 chips.\n");
fw_notify(" Cameras, audio devices etc. won't work on "
"this controller with this driver version.\n");
}
return 0;

fail_self_id:
Expand Down

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