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Clarify the description of the bus_dmasync_op_t operation flags. This has

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been misleading and even wrong since the import of the page.
This commit is contained in:
Scott Long 2005-08-26 18:19:01 +00:00
parent 9e24bd90fe
commit 1cb112ab25
1 changed files with 12 additions and 15 deletions
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27
share/man/man9/bus_dma.9
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@ -244,28 +244,25 @@ allows the type of DMA operation that will be or has been performed
to be communicated to the system so that the correct coherency measures
are taken.
All operations specified below are performed from the CPU's
point of view (for a complete description, see the
point of view, where a read implies data coming from the device to the CPU, and
a write implies data going from the CPU to the device.
The operations are represented as bitfield flags that can be combined together,
though it only makes sense to combine PRE flags or POST flags, not both.
See the
.Fn bus_dmamap_sync
description below):
description below for more details on how to use these operations.
.Bl -tag -width BUS_DMASYNC_POSTWRITE
.It Dv BUS_DMASYNC_PREREAD
Perform any synchronization required after an update of memory by the CPU
but prior to DMA read operations.
Perform any synchronization required prior to an update of memory by the DMA
operation.
.It Dv BUS_DMASYNC_PREWRITE
Perform any synchronization required after an update of memory by the CPU
but prior to DMA write operations.
.It Dv BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE
Perform any synchronization required prior to a combination of DMA read
and write operations.
and prior to DMA write operations.
.It Dv BUS_DMASYNC_POSTREAD
Perform any synchronization required after DMA read operations, but prior
to CPU access of the memory.
Perform any synchronization required after DMA read operations and prior to
CPU access to the memory.
.It Dv BUS_DMASYNC_POSTWRITE
Perform any synchronization required after DMA write operations, but prior
to CPU access of the memory.
.It Dv BUS_DMASYNC_POSTREAD|BUS_DMASYNC_POSTWRITE
Perform any synchronization required after a combination of DMA read
and write operations.
Perform any synchronization required after DMA write operations.
.El
.It Vt bus_dma_lock_t
Client specified lock/mutex manipulation method.