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Date:   Tue, 28 Sep 2021 08:57:51 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
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Subject: Re: [RFC 06/20] iommu: Add iommu_device_init[exit]_user_dma
 interfaces
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On Tue, Sep 28, 2021 at 07:30:41AM +0000, Tian, Kevin wrote:

> > Also, don't call it "hint", there is nothing hinty about this, it has
> > definitive functional impacts.
> 
> possibly dma_mode (too broad?) or dma_usage

You just need a flag to specify if the driver manages DMA ownership
itself, or if it requires the driver core to setup kernel ownership

DMA_OWNER_KERNEL
DMA_OWNER_DRIVER_CONTROLLED

?

There is a bool 'suprress_bind_attrs' already so it could be done like
this:

 bool suppress_bind_attrs:1;

 /* If set the driver must call iommu_XX as the first action in probe() */
 bool suppress_dma_owner:1;

Which is pretty low cost.

Jason