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Subject: Re: [PATCH 01/18] dmaengine: of-dma: Add support for optional router
 configuration callback
To:     Vinod Koul <vkoul@kernel.org>
CC:     <nm@ti.com>, <ssantosh@kernel.org>, <robh+dt@kernel.org>,
        <vigneshr@ti.com>, <dan.j.williams@intel.com>, <t-kristo@ti.com>,
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        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <dmaengine@vger.kernel.org>
References: <20200930091412.8020-1-peter.ujfalusi@ti.com>
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 <20201007054404.GR2968@vkoul-mobl>
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 <45adb88b-1ef8-1fbf-08c1-9afc6ea4c6f0@ti.com>
 <20201028055531.GH3550@vkoul-mobl>
From:   Peter Ujfalusi <peter.ujfalusi@ti.com>
Message-ID: <cf3d3de0-223b-4846-bd9f-b78654ae2d08@ti.com>
Date:   Wed, 28 Oct 2020 11:56:06 +0200
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Hi Vinod,

On 28/10/2020 7.55, Vinod Koul wrote:

>> To summarize:
>> In of_dma_route_allocate() the router does not yet know the channel we
>> are going to get.
>> In of_dma_xlate() the DMA driver does not yet know if the channel will
>> use router or not.
>> I need to tell the router the event number it has to send, which is
>> based on the channel number I got.
> 
> Sounds reasonable, btw why not pass this information in xlate. Router
> will have a different xlate rather than non router right, or is it same.

Yes, the router's have their separate xlate, but in that xlate we do not
yet have a channel. I don't know what is the event I need to send from
the router to trigger the channel.

> If this information is anyway available in DT might be better to get it
> and use from DT

Without a channel number I can not do anything.
It is close to a chicken and egg problem.

- Péter

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