Re: [Linaro-mm-sig] Re: Sharing dma-bufs using a driver-private interconnect

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Fri, 2025-05-16 at 10:44 +0200, Christian König wrote:
> Hi Thomas,
> 
> On 5/16/25 10:33, Thomas Hellström wrote:
> > Hi!
> > 
> > I previously discussed this with Simona on IRC but would like to
> > get
> > some feedback also from a wider audience:
> > 
> > We're planning to share dma-bufs using a fast interconnect in a way
> > similar to pcie-p2p:
> > 
> > The rough plan is to identify dma-bufs capable of sharing this way
> > by
> > looking at the address of either the dma-buf ops and / or the
> > importer_ops to conclude it's a device using the same driver (or
> > possibly child driver) and then take special action when the dma-
> > addresses are obtained. Nothing visible outside of the xe driver or
> > its
> > child driver.
> 
> As far as I can see that should work and we have recommended doing
> exactly that to multiple people in the past.
>  
> > Are there any absolute "DON'T"s or recommendations to keep in mind
> > WRT
> > to this approach?
> 
> My only requirement is that you write up some documentation
> (preferable either in drivers/dma-buf/dma-buf.c or
> Documentation/driver-api/dma-buf.rst) how drivers should do this,
> what the implications with the rest of the DMA-buf interface is
> etc... etc...
> 
> The goal is to nail down how to do driver private interfaces without
> breaking interoperability with drivers who don't participate in that.

Ok, Will ensure that we adhere to this.

Thanks,
Thomas


> 
> Regards,
> Christian.
> 
> > 
> > Thanks,
> > Thomas
> > 
> )
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