iwlwifi: dma mapping read and write changes

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When iwlwifi runs on IOMMU, IOMMU generates a lot of PTE write faults
because PTE write bit is not set on some of PTE's. This is because iwlwifi
driver calls DMA mapping with PCI_DMA_TODEVICE which is read only in mapping
PTE. But iwlwifi device actually writes to the mapped page to update its contents.
This issue is not exposed in swiotlb. But VT-d hardware can capture this fault and
stop the fault transaction.

The iwl TX command contains a scratch field that is updated by uCode to
indicate retry counts. For 5000 series the patch is required also for
regular frames, but this patch does not differenciate.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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This commit is contained in:

Fenghua Yu 2009-02-18 15:54:33 -08:00 • committed by John W. Linville

parent 7dc45f25d3

commit 96891ceeda

2 changed files with 4 additions and 4 deletions

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2

drivers/net/wireless/iwlwifi/iwl-agn.c

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6

drivers/net/wireless/iwlwifi/iwl-tx.c

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