RE: PCIe dmaengine driver on both x86 and ARM64

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> On Thu, Oct 27, 2016 at 02:31:08PM +0000, Bharat Kumar Gogada wrote:
> > > On Thu, Oct 27, 2016 at 12:57:08PM +0000, Bharat Kumar Gogada wrote:
> > > > Hi All,
> > > >
> > > > We have a PCIe end point with DMA controller in it.
> > > > We are planning to code using DMA frame work for this DMA controller.
> > > >
> > > > The PCIe End Point can be used on both ARM64 and x86 platforms.
> > > >
> > > > We are planning to develop dmaengine driver and client driver model.
> > > >
> > > > In ARM64 case dmaengine driver and client driver are probed using
> > > > device tree and also channel information is also obtained from device tree.
> > >
> > > I think more details are necessary here.
> > >
> > > Why is *anything* necessary in the DT if this is contained within a
> > > (probeable) PCIe endpoint?
> >
> > Thanks Mark.
> >
> > Yes as you said it is PCIe probeable device, sorry I missed some information, in
> case of ARM64
> > if we invoke client driver from device tree where we can pass channel
> information
> > such as number of channels, direction and other things.  So in this case how
> will client driver request
> > the channel it want to use, to dmaengine driver ?
> >
> > In case of x86 on what basis client driver can be probed and request the dma
> channels, if we already use
> > Vendor and device id for dmaengine driver ?
> 
> ACPI what else..
> 
> You can the request lines in client ACPI data and it can use to filter the
> request. There are already dmaengine drivers which use ACPI, so please check
> the source..
> 
Thanks vinod.

We have  a scenario where DMA client driver needs to access PCI bars of end point, but the 
DMA core driver is the one which has access to pcie resources. Is there any way we can pass
this bar information to client driver through DMA framework ?    

Thanks & Regards,
Bharat


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