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From: Vinod Koul <vkoul@kernel.org>
To: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: robh+dt@kernel.org, dmaengine@vger.kernel.org,
	linux-kernel@vger.kernel.org, dan.j.williams@intel.com,
	devicetree@vger.kernel.org
Subject: Re: [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains
Date: Thu, 12 Sep 2019 22:33:12 +0530
Message-ID: <20190912170312.GD4392@vkoul-mobl> (raw)
In-Reply-To: <a452cd06-79ca-424d-b259-c8d60fc59772@ti.com>

On 09-09-19, 09:30, Peter Ujfalusi wrote:

> >> or domain-dma-controller?
> > 
> > I feel dma-domain-controller sounds fine as we are defining domains for
> > dmaengine. Another thought which comes here is that why not extend this to
> > slave as well and define dma-domain-controller for them as use that for
> > filtering, that is what we really need along with slave id in case a
> > specific channel is to be used by a peripheral
> > 
> > Thoughts..?
> 
> I have thought about this, we should be able to drop the phandle to the
> dma controller from the slave binding just fine.
> 
> However we have the dma routers for the slave channels and there is no
> clear way to handle them.
> They are not needed for non slave channels as there is no trigger to
> route. In DRA7 for example we have an event router for EDMA and another
> one for sDMA. If a slave device is to be serviced by EDMA, the EDMA
> event router needs to be specified, for sDMA clients should use the sDMA
> event router.

So you have dma, xbar and client? And you need to use a specfic xbar,
did i get that right?

> In DRA7 case we don't really have DMA controllers for domains, but we
> use the DMA which can service the peripheral better (sDMA is better to
> be used for UART, but can not be used for McASP for example)
> 
> Then we have the other type of DMA router for daVinci/am33xx/am43xx
> where the crossbar is not for the whole EDMA controller like in DRA7,
> but we have small crossbars for some channels.
> 
> Other vendors have their own dma router topology..
> 
> Too many variables to handle the cases without gotchas, which would need
> heavy churn in the core or in drivers.

-- 
~Vinod

  reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 14:18 [RFC 0/3] dmaengine: Support for DMA domain controllers Peter Ujfalusi
2019-09-06 14:18 ` [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains Peter Ujfalusi
2019-09-08  7:47   ` Peter Ujfalusi
2019-09-08 12:10     ` Vinod Koul
2019-09-09  6:30       ` Peter Ujfalusi
2019-09-12 17:03         ` Vinod Koul [this message]
2019-09-13  7:21           ` Peter Ujfalusi
2019-09-13 10:36             ` Vinod Koul
2019-09-13 12:19               ` Peter Ujfalusi
2019-09-13 13:33                 ` Vinod Koul
2019-09-08 12:06   ` Vinod Koul
2019-09-09  6:00     ` Peter Ujfalusi
2019-09-06 14:18 ` [RFC 2/3] dmaengine: of_dma: Function to look up the DMA domain of a client Peter Ujfalusi
2019-09-08 12:12   ` Vinod Koul
2019-09-06 14:18 ` [RFC 3/3] dmaengine: Support for requesting channels preferring DMA domain controller Peter Ujfalusi
2019-09-08  7:46   ` Peter Ujfalusi
2019-09-08 12:15   ` Vinod Koul
2019-09-09  5:56     ` Peter Ujfalusi
2019-09-12 16:49       ` Vinod Koul
  -- strict thread matches above, loose matches on Subject: below --
2019-09-06 14:17 [RFC 0/3] dmaengine: Support for DMA domain controllers Peter Ujfalusi
2019-09-06 14:17 ` [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains Peter Ujfalusi

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