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Commit 96891cee authored by Fenghua Yu's avatar Fenghua Yu Committed by John W. Linville
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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: default avatarFenghua Yu <fenghua.yu@intel.com>
Acked-by: default avatarTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 7dc45f25

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

+1 −1
Original line number Diff line number Diff line
@@ -444,7 +444,7 @@ void iwl_hw_txq_free_tfd(struct iwl_priv *priv, struct iwl_tx_queue *txq) 
		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++) {

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

+3 −3
Original line number Diff line number Diff line
@@ -819,7 +819,7 @@ int iwl_tx_skb(struct iwl_priv *priv, struct sk_buff *skb) 
	 * within command buffer array. */

	txcmd_phys = pci_map_single(priv->pci_dev,

				    out_cmd, sizeof(struct iwl_cmd),

				    PCI_DMA_TODEVICE);

				    PCI_DMA_BIDIRECTIONAL);

	pci_unmap_addr_set(&out_cmd->meta, mapping, txcmd_phys);

	pci_unmap_len_set(&out_cmd->meta, len, sizeof(struct iwl_cmd));

	/* Add buffer containing Tx command and MAC(!) header to TFD's
@@ -968,7 +968,7 @@ int iwl_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd) 
			IWL_MAX_SCAN_SIZE : sizeof(struct iwl_cmd);



	phys_addr = pci_map_single(priv->pci_dev, out_cmd,

				   len, PCI_DMA_TODEVICE);

				   len, PCI_DMA_BIDIRECTIONAL);

	pci_unmap_addr_set(&out_cmd->meta, mapping, phys_addr);

	pci_unmap_len_set(&out_cmd->meta, len, len);

	phys_addr += offsetof(struct iwl_cmd, hdr);
@@ -1068,7 +1068,7 @@ static void iwl_hcmd_queue_reclaim(struct iwl_priv *priv, int txq_id, 
	pci_unmap_single(priv->pci_dev,

		pci_unmap_addr(&txq->cmd[cmd_idx]->meta, mapping),

		pci_unmap_len(&txq->cmd[cmd_idx]->meta, len),

		PCI_DMA_TODEVICE);

		PCI_DMA_BIDIRECTIONAL);



	for (idx = iwl_queue_inc_wrap(idx, q->n_bd); q->read_ptr != idx;

	     q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd)) {