linux-kernel - Re: [PATCH 7/9] spi: s3c64xx: Use dma_request_chan() directly for channel request

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Date:   Thu, 14 Nov 2019 10:09:33 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Andi Shyti <andi@...zian.org>
CC:     <linus.walleij@...aro.org>, <kgene@...nel.org>,
        <alexandre.belloni@...tlin.com>, <linux-arm-msm@...r.kernel.org>,
        <radu_nicolae.pirea@....ro>, <linux-spi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <krzk@...nel.org>,
        <bjorn.andersson@...aro.org>, <vkoul@...nel.org>,
        <agross@...nel.org>, <ldewangan@...dia.com>, <broonie@...nel.org>,
        <linux-tegra@...r.kernel.org>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <shawnguo@...nel.org>,
        <s.hauer@...gutronix.de>, <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 7/9] spi: s3c64xx: Use dma_request_chan() directly for
 channel request

On 14/11/2019 1.40, Andi Shyti wrote:
> Hi Peter,
> 
>>  	if (!is_polling(sdd)) {
>>  		/* Acquire DMA channels */
>> -		sdd->rx_dma.ch = dma_request_slave_channel_reason(&pdev->dev,
>> -								  "rx");
>> +		sdd->rx_dma.ch = dma_request_chan(&pdev->dev, "rx");
> 
> I have a little concern here. We have two funcions
> 'dma_request_chan' and  'dma_request_channel' don't we end up
> making some confusion here?
> 
> Wouldn't it make more sense renaming 'dma_request_chan' to
> 'dma_request_slave_channel_reason'?

The dma_request_channel() should go away. It was the old API before we
got the dma_slave_map for non DT (and non ACPI) platforms so we can get
rid of the filter function exports from DMA drivers to clients all over
the place.

I know there are users where they provide dummy filter function.

At the end the main API to request slave DMA channel should be
dma_request_chan()
For non slave channels (not HW triggered) we have dma_request_chan_by_mask()

Imoh the dma_request_slave_channel_compat() should also go away with time.

> 
> Thanks,
> Andi
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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