iwlwifi: dma mapping read and write changes
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>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index bcb94a0..b49f9f7 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -444,7 +444,7 @@
pci_unmap_single(dev,
pci_unmap_addr(&txq->cmd[index]->meta, mapping),
pci_unmap_len(&txq->cmd[index]->meta, len),
- PCI_DMA_TODEVICE);
+ PCI_DMA_BIDIRECTIONAL);
/* Unmap chunks, if any. */
for (i = 1; i < num_tbs; i++) {