RE: [PATCH]iwlan dma mapping read and write changes

[Bhavesh Davda]

Looks good to me. Ship it!

- Bhavesh
 
Bhavesh P. Davda

> -----Original Message-----
> From: iommu-bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx [mailto:iommu-
> bounces@xxxxxxxxxxxxxxxxxxxxxxxxxx] On Behalf Of Fenghua Yu
> Sent: Wednesday, February 11, 2009 10:27 AM
> To: David Woodhouse; Ingo Molnar; Stephen Rothwell; Andrew Morton;
> Johannes Berg; Emmanuel Grumbach; Tomas Winkler; Zhu Yi; Chris Wright
> Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; LKML
> Subject: [PATCH]iwlan dma mapping read and write changes
> 
> When iwlan 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 iwlan driver
> calls DMA
> mapping with PCI_DMA_TODEVICE which is read only in mapping PTE. But
> iwlan 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 following patch fixes the issue.
> 
> Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> 
> ---
> 
>  iwl-tx.c |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
> 
> --- a/drivers/net/wireless/iwlwifi/iwl-tx.c.orig	2009-02-10
> 21:28:45.000000000 -0800
> +++ b/drivers/net/wireless/iwlwifi/iwl-tx.c	2009-02-10
> 21:41:02.000000000 -0800
> @@ -148,7 +148,7 @@ static void iwl_hw_txq_free_tfd(struct i
>  		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++) {
> @@ -964,7 +964,7 @@ int iwl_tx_skb(struct iwl_priv *priv, st
>  	 * 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
> @@ -1115,7 +1115,7 @@ int iwl_enqueue_hcmd(struct iwl_priv *pr
>  			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);
> @@ -1212,7 +1212,7 @@ static void iwl_hcmd_queue_reclaim(struc
>  	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)) {
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