linux-kernel - Re: [PATCH 2/3] spi: spi-xilinx: Clear dma

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Message-ID: <20130604173632.GM31367@sirena.org.uk>
Date:	Tue, 4 Jun 2013 18:36:32 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Michal Simek <michal.simek@...inx.com>
Cc:	linux-kernel@...r.kernel.org, Michal Simek <monstr@...str.eu>,
	Peter Crosthwaite <pcrost@...inx.com>,
	Grant Likely <grant.likely@...aro.org>,
	spi-devel-general@...ts.sourceforge.net
Subject: Re: [PATCH 2/3] spi: spi-xilinx: Clear dma_mask for xilinx spi
 controller

On Tue, Jun 04, 2013 at 04:02:35PM +0200, Michal Simek wrote:
> From: Michal Simek <monstr@...str.eu>
> 
> mmc_spi driver tests if dma is available
> through spi->master->dev.parent->dma_mask.
> Microblaze supports DMA but xilinx_spi IP doesn't.
> That's why clear dma_mask in the driver.

> +	/* clear the dma_mask, to try to disable use of dma */
> +	master->dev.dma_mask = 0;
> +

This looks like a bodge in the wrong place.  Either the device
registration is incorrect in that it advertises DMA when none is
available or the SPI driver ought to be offering the MMC driver a more
sensible way of advertising this limitation.  My first thought is the
former but I didn't check where dma_mask is getting set.

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