linux-toradex.git/drivers/ntb, branch v4.4-rc6

NTB: fix 32-bit compiler warning

2015-11-08T21:24:43+00:00

resource_size_t may be 32-bit wide on some architectures, which causes
this warning when building the NTB code:

drivers/ntb/ntb_transport.c: In function 'ntb_transport_link_work':
drivers/ntb/ntb_transport.c:828:46: warning: right shift count >= width of type [-Wshift-count-overflow]

The warning is harmless but can be avoided by using the upper_32_bits()
macro.

Signed-off-by: Arnd Bergmann 
Fixes: e26a5843f7f5 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Jon Mason

NTB: unify translation addresses

2015-11-08T21:11:21+00:00

There is no need for the upstream and downstream addresses to be different
for the NTB configs. Go to using a single set of address. It is still
possible to configure them differently using module parameter override
however.

Signed-off-by: Dave Jiang 
Acked and Tested-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: invalid buf pointer in multi-MW setups

2015-11-08T21:11:21+00:00

Order of operations issue with the QP Num and MW count, which would
result in the receive buffer pointer being invalid if there are more
than 1 MW.  Corrected with parenthesis to enforce the proper order of
operations.

Reported-by: John I. Kading 
Signed-off-by: Jon Mason

NTB: remove unused variable

2015-11-08T21:11:21+00:00

These variables were not used anywhere. So remove them.

Signed-off-by: Sudip Mukherjee 
Signed-off-by: Jon Mason

NTB: fix access of free-ed pointer

2015-11-08T21:11:21+00:00

We were accessing nt->mw_vec after freeing it. Fix the error path so
that we free nt->mw_vec after we have finished using it.

Signed-off-by: Sudip Mukherjee 
Signed-off-by: Jon Mason

NTB: Fix issue where we may be accessing NULL ptr

2015-11-08T21:11:21+00:00

smatch detected an issue in the function ntb_transport_max_size() where
we could be dereferencing a dma channel pointer when it is NULL.

Reported-by: Dan Carpenter 
Signed-off-by: Dave Jiang 
Signed-off-by: Jon Mason

NTB: Fix range check on memory window index

2015-09-07T19:27:12+00:00

The range check must exclude the upper bound.

Signed-off-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Improve index handling in B2B MW workaround

2015-09-07T19:27:12+00:00

Check that b2b_mw_idx is in range of the number of memory windows when
initializing the device.  The workaround is considered to be in effect
only if the device b2b_idx is exactly UINT_MAX, instead of any index
past the last memory window.

Only print B2B MW workaround information in debugfs if the workaround is
in effect.

Signed-off-by: Allen Hubbe 
Signed-off-by: Jon Mason

NTB: Use unique DMA channels for TX and RX

2015-09-07T19:17:09+00:00

Allocate two DMA channels, one for TX operation and one for RX
operation, instead of having one DMA channel for everything. This
provides slightly better performance, and also will make error handling
cleaner later on.

Signed-off-by: Dave Jiang 
Signed-off-by: Jon Mason

NTB: Remove dma_sync_wait from ntb_async_rx

2015-09-07T19:17:08+00:00

The dma_sync_wait can hurt the performance of workloads mixed with both
large and small frames.  Large frames will be copied using the dma
engine.  Small frames will be copied by the cpu.  The dma_sync_wait
prevents the cpu and dma engine copying in parallel.

In the period where the cpu is copying, the dma engine is stopped.  The
dma engine is not doing any useful work to copy large frames during that
time, and the additional time to restart the dma engine for the next
large frame.  This will decrease the throughput for the portion of a
workload with large frames.

In the period where the dma engine is copying, the cpu is held up
waiting for dma to complete.  The small frames processing will be
delayed until the dma is complete.  The RX frames are completed
in-order, and the processing of small frames takes very little time, so
dma_sync_wait may have an insignificant impact on the respose time of
frames.  The more significant impact is to the system, because the delay
in dma_sync_wait is implemented as busy non-blocking wait.  This can
prevent the delayed core from doing any useful work, even if it could be
processing work for other drivers, unrelated to transport RX processing.

After applying the earlier patch to fix out-of-order RX acknoledgement,
the dma_sync_wait is no longer necessary.  Remove it, so that cpu memcpy
will proceed immediately for small frames, in parallel with ongoing dma
for large frames.  Do not hold up the cpu from doing work while dma is
in progress.  The prior fix will continue to ensure in-order completion
of the RX frames to the upper layer, and in-order delivery of the RX
acknoledgement.

Signed-off-by: Allen Hubbe 
Signed-off-by: Jon Mason