[PATCH v2 2/5] dma-mapping: Introduce dma_iommu_detach_device() API

Thierry Reding thierry.reding at gmail.com
Thu Apr 26 05:11:36 PDT 2018


On Wed, Apr 25, 2018 at 08:19:34AM -0700, Christoph Hellwig wrote:
> On Wed, Apr 25, 2018 at 12:10:48PM +0200, Thierry Reding wrote:
> > From: Thierry Reding <treding at nvidia.com>
> > 
> > The dma_iommu_detach_device() API can be used by drivers to forcibly
> > detach a device from an IOMMU that architecture code might have attached
> > to. This is useful for drivers that need explicit control over the IOMMU
> > using the IOMMU API directly.
> 
> Given that no one else implements it making it a generic API seems
> rather confusing.  For now I'd rename it to
> arm_dma_iommu_detach_device() and only implement it in arm.

That'd be suboptimal because this code is used on both 32-bit and 64-bit
ARM. If we make the function 32-bit ARM specific then the driver code
would need to use an #ifdef to make sure compilation doesn't break on
64-bit ARM.

Thierry
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