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  1. 04 Mar, 2013 5 commits
  3. 28 Feb, 2013 4 commits
    • Johannes Berg's avatar
      iwlwifi: use coherent DMA memory for command header · 38c0f334
      Johannes Berg authored 
      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: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      38c0f334
    • Emmanuel Grumbach's avatar
      iwlwifi: disable 8K A-MSDU by default · aed7d9ac
      Emmanuel Grumbach authored 
      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: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      aed7d9ac
    • Johannes Berg's avatar
      iwlwifi: rename IWL_MAX_CMD_TFDS to IWL_MAX_CMD_TBS_PER_TFD · 1afbfb60
      Johannes Berg authored 
      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: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      1afbfb60
    • Johannes Berg's avatar
      iwlwifi: don't map complete commands bidirectionally · 98891754
      Johannes Berg authored 
      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: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      98891754
  5. 27 Feb, 2013 2 commits
  7. 26 Feb, 2013 2 commits
    • Johannes Berg's avatar
      iwlwifi: mvm: fix AP/GO mode station removal · 38a12b5b
      Johannes Berg authored 
      When stations are removed while packets are in the queue,
we drain the queues first, and then remove the stations.
If this happens in AP mode while the interface is removed
the MAC context might be removed from the firmware before
we removed the station(s), resulting in a SYSASSERT 3421.
This is because we remove the MAC context from the FW in
stop_ap(), but only flush the station drain work later in
remove_interface().

Refactor the code a bit to have a common MAC context
removal preparation first to solve this.
Reviewed-by: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      38a12b5b
    • Johannes Berg's avatar
      iwlwifi: always copy first 16 bytes of commands · 8a964f44
      Johannes Berg authored 
      The FH hardware will always write back to the scratch field
in commands, even host commands not just TX commands, which
can overwrite parts of the command. This is problematic if
the command is re-used (with IWL_HCMD_DFL_NOCOPY) and can
cause calibration issues.

Address this problem by always putting at least the first
16 bytes into the buffer we also use for the command header
and therefore make the DMA engine write back into this.

For commands that are smaller than 16 bytes also always map
enough memory for the DMA engine to write back to.

Cc: stable@vger.kernel.org
Reviewed-by: default avatarEmmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
      8a964f44
  9. 22 Feb, 2013 3 commits
  11. 18 Feb, 2013 24 commits
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