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  1. 28 2月, 2013 4 次提交
    • J
      iwlwifi: use coherent DMA memory for command header · 38c0f334
      由 Johannes Berg 提交于 
      Recently in commit 8a964f44
("iwlwifi: always copy first 16 bytes of commands") we fixed
the problem that the hardware writes back to the command and
that could overwrite parts of the data that was still needed
and would thus be corrupted.

Investigating this problem more closely we found that this
write-back isn't really ordered very well with respect to
other DMA traffic. Therefore, it sometimes happened that the
write-back occurred after unmapping the command again which
is clearly an issue and could corrupt the next allocation
that goes to that spot, or (better) cause IOMMU faults.

To fix this, allocate coherent memory for the first 16 bytes
of each command, containing the write-back part, and use it
for all queues. All the dynamic DMA mappings only need to be
TO_DEVICE then. This ensures that even when the write-back
happens "too late" it can't hit memory that has been freed
or a mapping that doesn't exist any more.

Since now the actual command is no longer modified, we can
also remove CMD_WANT_HCMD and get rid of the DMA sync that
was necessary to update the scratch pointer.
Reviewed-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
      38c0f334
    • E
      iwlwifi: disable 8K A-MSDU by default · aed7d9ac
      由 Emmanuel Grumbach 提交于 
      Supporting 8K A-MSDU means that we need to allocate order 1
pages for every Rx packet. Even when there is no traffic.
This adds stress on the memory manager. The handling of
compound pages is also less trivial for the memory manager
and not using them will make the allocation code run faster
although I didn't really measure.
Eric also pointed out that having huge buffers with little
data in them is not very nice towards the TCP stack since
the truesize of the skb is huge. This doesn't allow TCP
to have a big Rx window.
See https://patchwork.kernel.org/patch/2167711/ for details.

Note that very few vendors will actually send A-MSDU.
Disable this feature by default.
Signed-off-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
      aed7d9ac
    • J
      iwlwifi: rename IWL_MAX_CMD_TFDS to IWL_MAX_CMD_TBS_PER_TFD · 1afbfb60
      由 Johannes Berg 提交于 
      The IWL_MAX_CMD_TFDS name for this constant is wrong, the
constant really indicates how many TBs we can use in the
driver for a single command TFD, rename the constant and
also add a comment explaining it.
Reviewed-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
      1afbfb60
    • J
      iwlwifi: don't map complete commands bidirectionally · 98891754
      由 Johannes Berg 提交于 
      The reason we mapped them bidirectionally was that not doing
so had caused IOMMU exceptions, due to the fact that the HW
writes back into the command. Now that the first part of the
command including the write-back part is always in the first
buffer, we don't need to map the remaining buffer(s) bidi
and can get rid of the special-casing for commands.

This is a requisite patch for another one to fix DMA mapping.
Reviewed-by: NEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
      98891754
  3. 27 2月, 2013 4 次提交
  5. 23 2月, 2013 3 次提交
  7. 19 2月, 2013 16 次提交
  9. 15 2月, 2013 10 次提交
  11. 13 2月, 2013 1 次提交
  13. 12 2月, 2013 2 次提交