As it seems, some host controllers have issues that can cause them to
skip cycles now and then when using large packets. I suspect that this
is due to DMA not succeeding in time. If the transmit fifo can't contain
more than one packet (big packets), the DMA should provide a new packet
each cycle (125us). I am under the impression that my current PCI
express test system can't guarantee this.
In any case, the patch tries to provide a workaround as follows:
The DMA program descriptors are modified such that when an error occurs,
the DMA engine retries the descriptor the next cycle instead of
stalling. This way no data is lost. The side effect of this is that
packets are sent with one cycle delay. This however might not be that
much of a problem for certain protocols (e.g. AM824). If they use
padding packets for e.g. rate matching they can drop one of those to
resync the streams.
The amount of skips between two userspace wakeups is counted. This
number is then propagated to userspace through the upper 16 bits of the
'dropped' parameter. This allows unmodified userspace applications due
to the following:
1) libraw simply passes this dropped parameter to the user application
2) the meaning of the dropped parameter is: if it's nonzero, something
bad has happened. The actual value of the parameter at this moment does
not have a specific meaning.
A libraw client can then retrieve the number of skipped cycles and
account for them if needed.
Signed-off-by: Pieter Palmers <pieterp@joow.be>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Remove unnecessary includes, add missing includes.
Use forward type declarations for some structs.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Adjust tabulators, line wraps, empty lines, and comment style.
Update comments in ieee1394_transactions.h and highlevel.h.
Fix typo in comment in csr.h.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Signed-off-by: Ben Collins <bcollins@ubuntu.com>
Lots of this patch is trivial code cleanups (static vars were being
intialized to 0, etc).
There's also some fixes for ISO transmits (max buffer handling).
Aswell, we have a few fixes to disable IRM capabilites correctly. We've
also disabled, by default some generally unused EXPORT symbols for the
sake of cleanliness in the kernel. However, instead of removing them
completely, we felt it necessary to have a config option that allowed
them to be enabled for the many projects outside of the main kernel tree
that use our API for driver development.
The primary reason for this patch is to revert a MODE6->MODE10 RBC
conversion patch from the SCSI maintainers. The new conversions handled
directly in the scsi layer do not seem to work for SBP2. This patch
reverts to our old working code so that users can enjoy using Firewire
disks and dvd drives again.
We are working with the SCSI maintainers to resolve this issue outside
of the main kernel tree. We'll merge the patch once the SCSI layer's
handling of the MODE10 conversion is working for us.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Pieter Palmers