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

[Chris Wright]

* Fenghua Yu (fenghua.yu@xxxxxxxxx) wrote:
> 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.

Yes, plain old driver bug!  This fixes the iwlagn vt-d issue.


> Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>

Tested-by: Chris Wright <chrisw@xxxxxxxxxxxx>

thanks,
chris
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