From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 5/6] dma-mapping: support fsl-mc bus
Date: Thu, 8 Mar 2018 08:41:15 +0100
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To: Nipun Gupta <nipun.gupta@nxp.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>, "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>, "stuyoder@gmail.com" <stuyoder@gmail.com>, Bharat Bhushan <bharat.bhushan@nxp.com>, "catalin.marinas@arm.com" <catalin.marinas@arm.com>, "joro@8bytes.org" <joro@8bytes.org>, "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>, "will.deacon@arm.com" <will.deacon@arm.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Leo Li <leoyang.li@nxp.com>, "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>, "robh+dt@kernel.org" <robh+dt@kernel.org>, "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>, "shawnguo@kernel.org" <shawnguo@kernel.org>, Laurentiu Tudor <laurentiu.tudor@nxp.com>, Robin Murphy <robin.murphy@arm.com>, Christoph Hellwig <hch@lst.de>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infra>
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On Tue, Mar 06, 2018 at 04:41:56AM +0000, Nipun Gupta wrote:
> Sorry for asking a trivial question - looking into dma_configure() I see that
> PCI is used in the start and the end of the API.
> In the end part pci_put_host_bridge_device() is called.
> So are two bus callbacks something like 'dma_config_start' & 'dma_config_end'
> will be required where the former one will return "dma_dev"?

I'd just use dma_configure as the callback.

Currently the of_dma_configure and acpi_dma_configure are only used
for PCI anyway, as no one else sets a non-NULL dma dev.   For fsl-mc
I suspect only of_dma_configure is relevanet, so just call that directly.
If at some point we get enough busses with either OF or ACPI we could
create a helper called from ->dma_configure for that.