linux-kernel - Re: [PATCH V3 2/5] spi: s3c64xx: added support for polling mode

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Date:	Thu, 4 Apr 2013 11:15:46 +0530
From:	Girish KS <girishks2000@...il.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	spi-devel-general@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	grant.likely@...retlab.ca, t.figa@...sung.com
Subject: Re: [PATCH V3 2/5] spi: s3c64xx: added support for polling mode

On Wed, Apr 3, 2013 at 5:19 PM, Mark Brown
<broonie@...nsource.wolfsonmicro.com> wrote:
> On Wed, Apr 03, 2013 at 05:00:04PM +0530, Girish KS wrote:
>> On Mon, Apr 1, 2013 at 6:42 PM, Mark Brown
>
>> >> -     if (!sdd->pdev->dev.of_node) {
>> >> +     if (!sdd->pdev->dev.of_node && !is_polling(sdd)) {
>> >>               res = platform_get_resource(pdev, IORESOURCE_DMA,  0);
>> >>               if (!res) {
>> >>                       dev_err(&pdev->dev, "Unable to get SPI tx dma "
>
>> > It seems like it'd be sensible to also handle failure to get the DMA
>> > resource by going into polling mode.
>
>> There are 2 cases currently i have identified and handled,
>> 1. The SoC's dont have DMA support for spi controller. For such SoC's we
>>  would not add the dma resource in the spi dts node. In this case the probe
>>  would return error if failure for DMA resuorce is handled.
>
> That's not what the code currently does...
>
>> 2. The SoC has a DMA support for SPI controller, but due to some x
>> reason(H/W bug),
>>  the driver would force polling mode by enabling
>> S3C64XX_SPI_QUIRK_POLL in driver
>>  data. For such SoC's there would be a dma entry in the spi controller
>> dts node, and
>>  probe can handle failure for DMA resource successfully.
>
>> To handle above both situations successfully if
>> (!sdd->pdev->dev.of_node && !is_polling(sdd)) is used.
>
> Right, that's what the code currently does but what I'm suggesting is
> that this isn't the most helpful thing to do and that printing a big
> warning then soldiering on in polling mode might be more useful.

Ok I got it. will do it.

Thanks Mark
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