off the stack, initialized to default values, and then filled in with
driver-specific values, all without having to worry about the numerous
other fields in the tag. The resulting template is then passed into
busdma and the normal opaque tag object created. See the man page for
details on how to initialize a template.
Templates do not support tag filters. Filters have been broken for many
years, and only existed for an ancient make/model of hardware that had a
quirky DMA engine. Instead of breaking the ABI/API and changing the
arugment signature of bus_dma_tag_create() to remove the filter arguments,
templates allow us to ignore them, and also significantly reduce the
complexity of creating and managing tags.
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D22906
Describe the role of tags and mapping objects as abstractions.
Describe static vs dynamic transaction types and give a brief overview
of the set of functions and object life cycles used for static vs
dynamic.
While here, fix a few other typos and expand a bit on parent tags.
Reviewed by: cem, imp
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D16652
The NetBSD Foundation states "Third parties are encouraged to change the
license on any files which have a 4-clause license contributed to the
NetBSD Foundation to a 2-clause license."
This change removes clauses 3 and 4 from copyright / license blocks that
list The NetBSD Foundation as the only copyright holder.
Sponsored by: The FreeBSD Foundation
with bus_dmamap_create() and not only bus_dmamem_alloc() so move
the description of this flag up accordingly in order to document
this fact. While at, it refine this description with an application
example.
- Reword the description of BUS_DMA_NOCACHE as this flag is also
implemented on sparc64.
MFC after: 1 week
ago. Document the real behavior of bus_dma_tag_create, bus_dmamap_load,
and other functions. Also document their arguments and return values.
MFC After: 3 days
when it won't be called. The old wording was correct, but not
sufficiently specific to understand when and how it would be called.
The new wording describes the current implementation's usage (which
should be updated if other appropriate times are decided upon),
specifically that it is called only when the load operation is
deferred to keep the locking state consistent. When the operation
isn't deferred, the calling routine is assumed to have a coherent
locking world.
Reviewed by: scottl
the arguments to bus_dmamap_load, so don't use '...' but list the
actual args. '...' usually means a variable number of args (cf
printf(3)), but bus_dmamap_load takes a fixed number of arguments.
to just before bus_dmamem_free, which is (a) more logical; (b) likely
what was originally intended and (c) matches the order in the NAME and
FUNCTIONS sections.
