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iwlwifi: pcie: fix DMA memory mapping / unmapping

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commit 943309d4aa upstream.

22000 devices (previously referenced as A000) can support
short transmit queues. This means that we have less DMA
descriptors (TFD) for those shorter queues.
Previous devices must still have 256 TFDs for each queue
even if those 256 TFDs point to fewer buffers.

When I introduced support for the short queues for 22000
I broke older devices by assuming that they can also have
less TFDs in their queues. This led to several problems:

1) the payload of the commands weren't unmapped properly
   which caused the SWIOTLB to complain at some point.
2) the hardware could get confused and we get hardware
   crashes.

The corresponding bugzilla entries are:

https://bugzilla.kernel.org/show_bug.cgi?id=198201
https://bugzilla.kernel.org/show_bug.cgi?id=198265

Fixes: 4ecab56160 ("iwlwifi: pcie: support short Tx queues for A000 device family")
Reviewed-by: Sharon, Sara <sara.sharon@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Emmanuel Grumbach 2018-01-04 09:19:13 +02:00 • committed by Greg Kroah-Hartman
commit 8ec160c5f0
3 changed files with 14 additions and 15 deletions
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